Rays of the genus Potamotrygon, the river stingrays, are among the most extraordinary animals that are available to the freshwater aquarist. They are also among the most challenging to keep. While the likelihood of lasting success with these species is considerably greater than that of other rays (whether freshwater, marine or anything in between), a serious attempt to keep them should begin with a large measure of research, planning and patience. This involves:

1. developing an understanding of how these highly specialized creatures have physically and physiologically adapted to their natural environment, and
2. learning how to simulate this environment in a manner that meets the unique needs of each target species. With time and the necessary resources, river stingray keepers can construct a captive environment in which their animals can not only thrive, but in due course reproduce.

This piece discusses the morphology, reproduction and husbandry of the river stingrays. A previous piece discussed river stingray classification, distribution, ecology and conservation.

Morphology

Species of the genusPotamotrygon are roughly average in size among the batoids (i.e., rays and skates), ranging from approximately 25 cm in disc width to 100 cm or more. The smallest species of the genus, P. scobina, reaches 20.5 to 27 cm in disc width; P. brachyura, the largest species of the genus, is known to reach a disc width of as much as 150 cm. Generally, the disc is slightly longer than it is wide. Note that disc width (or DW) and disc length (or DL) are standard measurements of stingrays. Total length is generally not used, given that a portion of the tail is often missing.

The disc is formed mainly by greatly enlarged pectoral fins, which are fused to the head. Posteriorly it overlaps most of the pelvic fins. Although there are no dorsal or caudal fins, membranous skin folds (or finfolds) are present on both the upper and lower tail midlines. Compared to other members of their family, river stingrays have a tail (or caudal appendage) that is stout and short (typically shorter than disc length). The dorsal surfaces of the disc and tail are often quite spiny, being covered with denticles, thorns and tubercles.

Like other stingrays, fishes of this genus have venomous barbs (or caudal stings) located on the dorsal surface of their tails. Stings are hardened sections of dermal tissue with acute distal tips. They are continuously shed and replaced. An individual may bear up to four stings at a time. The sting is well developed in Potamotrygon. It is comprised of a spine, an integumentary sheath and venom glands. The spine, which gives the surface of the sting its stiffness, is composed of dentin. It contains several small, lateral serrations oriented toward the base. Special glands at the base produce venom that is carried along longitudinal grooves. When the spine is relaxed, it rests on a wedge-shaped piece of tissue that keeps it bathed in venom and mucus.

Most potamotrygonids bear highly distinctive markings. These include various spots, reticulations and ocelli under a grey, black or brown background coloration. Patterns of pigmentation are presumed to be species-specific.

Reproduction

The Potamotrygonidae are similar to marine elasmobranchs in that they are characterized by late maturation, slow growth and low fecundity. The hydrologic cycle appears to exert an appreciable influence on the reproductive cycle of potamotrygonids. Studies suggest that the reproductive cycle includes a resting interval in at least some populations. As males reach spawning condition, they begin to seek out and chase females. Courtship can become violent, particularly if a chosen female is unreceptive to a male's advances; males will resort to biting and wrestling in order to assume a belly-to-belly position. Copulation transpires quickly, with the male inserting a clasper into the female's cloaca and releasing milt. If a successful fertilization occurs, the oviduct undergoes changes that allow it to function as a uterus.

All known freshwater stingrays employ a reproductive strategy called matrotrophic viviparity, wherewith uterine milk (or histotrophe) secreted by specialized uterine filaments (or trophonemata) nourishes the developing embryo during gestation. Gestation may take place either intermittently or throughout the year. The gestation period is variable among wild populations, lasting from 3-12 months; however, in captive populations, this stage generally lasts from 9-12 months. The birthing season can last from 3-4 months. Depending upon species, environmental conditions and the fitness of the mother, the number of offspring produced from each gestation is usually from 2-7, though litters as large as 15 have been reported. The pups are born live and are fully formed. In captivity, pups are best transferred immediately after birth to a dedicated system for solitary grow-out. Absorption of the yolk sac lasts up to 7 days. By this time, pups can be offered a variety of live and frozen foods. With proper nutrition, excellent water quality and ample living space, growth is rapid.

Husbandry

One of the most important elements of a river stingray aquarium is the tank itself. Here, the best tank is a big tank. Some sources recommend minimum tank volumes of 90 gallons. Even so, one would do best to use a volume of 120 gallons or more. A "long" tank is preferable to a "tall" tank, as the inhabitants will make better use of horizontal (i.e., bottom) space than vertical space. Thus, even the smaller species need a minimum tank size of 48 in long x 30 in wide x 20 in tall per trio (i.e., one male and two females).

A river stingray aquarium should have a sandy substrate. The sand bed should be deep enough that the rays can completely bury themselves (i.e., such that only their eyes will be visible).

Sub-gravel heaters should never be used, as they may burn the animal. Conventional heaters (either submersible or non-submersible) should instead be used, albeit with a protective cover (such as a Hagen® heater guard).

As river stingrays are somewhat sensitive to suboptimal water conditions, they require highly effectual water treatment/filtration. Only an efficient biofilter (such as a trickle filter with high surface area media) should be relied upon to carry out biofiltration. Aggressive mechanical filtration (and frequent cleaning of sponges/pads) is advisable, as rays can be unusually messy eaters. Chemical filtration (particularly those types that remove metals) can be very useful in protecting the animals from contaminants and bioaccumulations.

River stingrays are not especially territorial; provided that a large enough aquarium is used, they may be kept in groups or with certain other types of fish. They cohabitate especially well with surface dwelling fishes such as gars, which tend to stay out of their way. They should not be housed with aggressive or nippy fishes such as piranhas, puffers and certain cichlids. Caution should be exercised if they are to be housed with plecos (e.g., Plecostomus sp.), which tend to irritate them by sucking at their disc. While fast and flighty little fishes such as tetras will generally be safe, river stingrays will eat any small fish that they can catch.

River stingrays benefit from a highly varied diet. They may be offered some combination of live items such as blackworms, earthworms (chopped), bloodworms, ghost shrimp and/or grass shrimp, with frozen items such as clam, mussel, silversides, krill and/or mysis shrimp.

Great care must be taken at all times when handling stingrays. It is far more preferable to capture them with a bucket or bowl than with a net. Never lose sight of these animals when handling or working around them. River stingray injuries are extremely painful and potentially life threatening. If a blood vessel is punctured, apply hard pressure directly to the wound to minimize any bleeding. The affected area should immediately be placed under water that is as hot as the victim can tolerate. After most of the pain has subsided, the wound can be cleaned by way of Betadine™ treatment followed by a rinse with disinfectant soap. Then--no matter how minor the injury appears to be--seek immediate medical attention. The examination should include radiology to locate any fragments of the sting that may be embedded in the wound. Return to the physician at the first sign of any infection.

Conclusion

Stingrays of the genus Potamotrygon can be stunning aquarium animals. While they have a much better record of captive survivability than other batoids, their husbandry is hardly undemanding or uncomplicated. In actual fact, properly caring for these unusual creatures requires a considerable amount of preparation and resources. Moreover, one must take precautions to avoid serious injury while handling or working around them. Still, a healthy river stingray is an exceptionally fascinating, beautiful creature and is definitely worth the extra effort. The relative ease with which Potamotrygon spp. can be successfully bred and reared makes them even more appealing. Breeding river stingrays is not only an interesting (and potentially very lucrative) activity, but is also important for conservation efforts in that it reduces demand for wild-caught specimens. With growing commercial production, one could hope that more river stingray species and varieties may be available to home aquarists in the very near future.

Sources

1. Kuba, Michael J., Ruth A. Byrne and Gordon M. Burghardt. (2010). A new method for studying problem solving and tool use in stingrays (Potamotrygon castexi). Animal Cognition, 13(3), 507-513.
2. Toffoli, Daniel, Tomas Hrbek, Maria Lúcia Góes de Araújo, Maurício Pinto de Almeida, Patricia Charvet-Almeida. (2008). A test of the utility of DNA barcoding in the radiation of the freshwater stingray genus Potamotrygon (Potamotrygonidae, Myliobatiformes). Genetics and Molecular Biology 31(1), 1-116.
3. de Araújo, Maria, Lúcia Góes, Patricia Charvet-Almeida, Mauricio Pinto de Almeida and Henrique Pereira, Brazil. (2004). Conservation perspectives and management challenges for freshwater stingrays. Ichthyology at the Florida Museum of Natural History. 14, 10-12.
4. Charvet-Almeida, Patricia, Maria Lúcia Góes de Araújo, Ricardo S. Rosa and Getúlio Rincón. (2002). Neotropical Freshwater Stingrays: diversity and conservation status. Ichthyology at the Florida Museum of Natural History. 14, 10-12.
5. de Araújo, Maria, Lúcia Góes, Patricia Charvet-Almeida, Mauricio Pinto de Almeida and Henrique Pereira, Brazil. (2004). Conservation perspectives and management challenges for freshwater stingrays. Ichthyology at the Florida Museum of Natural History. 14, 10-12.
6. Charvet-Almeida, Patricia, Maria Lúcia Góes de Araújo, Ricardo S. Rosa and Getúlio Rincón. (2002). Neotropical Freshwater Stingrays: diversity and conservation status. Ichthyology at the Florida Museum of Natural History. 14, 1-4.
7. http://www.monsterfishkeepers.com/forums/showthread.php?t=172190
8. http://fishbase.org/summary/FamilySummary.php?ID=21
9. http://www.cites.org/common/com/ac/20/e20-inf-08.pdf
10. http://www.raylady.com/Potamotrygon

The Amphiprion genus continues to offer some of the most well-loved and sought after species for the marine tank, and is ideally suited for commercial and hobbyist scale captive breeding, The genus contains some real beauties from Mother Nature's stable as well as some captive bred morphs that divide opinion on occasion.

If we combine the genus' usual good nature (through a pair can be very territorial) and ease of propagation in captivity, then no wonder the group is so well represented in aquaria and LFS across the world. There are though, a few rarities that are rarely imported and not yet commonly bred, one such species is Amphiprion chrysogaster the Mauritian Clownfish.

Chrysogaster sits within the Clarkii complex of clowns and is very similar to clarkii, sebae and allardi for example, though its limited geographical range makes for easy identification in the field. The fish reaches 15cm in length and can be recognised by the black tail with white upper band and white stripe to the upper rear portion of the dorsal. Juvenile specimens are much lighter in colour and present difficulties to easy identification.

To Mauritius

I've been keeping marine fish for a number of years now and I've been lucky enough to combine my hobby with a passion for scuba diving and seeing 'real' coral reefs. Not only does this hobby inspire my aquascaping attempts, but it has encouraged me to value wild reefs and to value them for their intrinsic value and ultimately the source of what has become a life-consuming passion.

Recently, I had the opportunity to travel to the small island of Mauritius. This tiny speck in the Indian Ocean, off the coast of Madagascar, is of course well known for its now extinct species - the Dodo being the one we all think of immediately - but it is also the subject of intense international efforts to save many more species that remain on the brink of extinction today.

I'd been lucky enough to visit some of the Island's last remaining patches of natural forest amidst seas of sugar cane and I was lucky enough to photograph Pink Pigeons, Echo Parakeets and the Mauritian Kestrel, all birds that were until a few years ago represented by a handful of specimens.

These threatened birds illustrate the problems faced by island species across the globe: islands hold many species that have developed in splendid isolation and are highly unsuited to compete with aggressive colonisers introduced from other parts of the world, be they hungry sailors, mongoose or rats - the native endemic species suffer. Small islands, atolls and isolated reefs are underwater mirrors of the terrestrial world and as eager as I was to see rare birds of prey I was also very keen to explore the reefs of Mauritius to see what could be seen.

I have to admit, i'd not been aware of chrysogaster before this trip became a reality. It was my good friend Dale Pritchard of Ecoreef UK who suggested I should make them a priority and even asked me to squeeze a few into my hand luggage (sorry Dale, you were joking right?) - Photos would have to suffice! This wasn't to be so easy though, but we'll come back to that...

Like most tropical islands, Mauritius is surrounded by barrier reefs with associated lagoon systems, the barrier reefs can be as little as a few hundred metres off shore or a few kilometres depending on topography, though in general the eastern side of the island has more extensive lagoon systems. The lagoons are subject to a great deal of pressure from tourism associated development and are in many areas now devoid of the large expanses of hermatypic corals they once held. Water sports activities and the need to provide easy swimming opportunities for guests have in the past won out over conservation efforts. There are some hints that this might be changing though and the recent tsunami have reminded Mauritians that their reefs and mangrove swamps are of significant import in protecting them from the ravages of the oceans in a world where sea level rise is likely.

The mangrove systems and of course the sea grass and Caulerpa beds of Mauritius are fascinating and deserve an article in themselves - I was lucky enough to explore these whist snorkelling and at low tide and witnessed the extraordinary habitat they offer for young fish that will later be found on the reef - but for now it is further out and deeper that I turn my attentions.

My first dives were on the south coast of the Island, an area still considered 'wild' by many. I'd discussed my desire to see the local clownfish with my guide from the Cabana Water Sports Centre at the Telfair hotel and he promised to take me to Anemone Pass, which sounded just what I was looking for. The visibility was poor but as we descended into a wide crack in the reef, the numbers of anemone became apparent and I was looking at scores of square metres of rock carpeted with Heteractis magnifica specimens. At first I couldn't see many hosting fish, there were good numbers of Dascyllus trimaculatus, but no clowns to be seen - darn this was going to be annoying so I switched on my camera and looked to the Dascyllus for a shot.

But no, there was no shutter noise, no flash firing and I looked in horror to see my camera housing was full of water and my Nikon was slowly turning to electronic soup. Needless to say I expressed my disappointment with some choice language but decided to complete the dive. Did I see any chrysogaster? no idea really.

To cheer me up I visited Mauritius' aquarium which featured the local undersea fauna - the stock is caught within metres of the bay under license from the authorities. Here I met Rasheed Ramjhun who guided me though the collection and here I met my first chrysogaster.

After several days of rinsing, stripping down and careful drying I decided to risk my housing again and managed to wedge my other Nikon (a D300s) into the housing originally made for a D200. It worked, to a certain extent, I could focus and fire the trigger and that was it, flash would be manual only. With some trepidation I took it snorkelling to ensure it was water tight before taking the plunge again.

By this time we'd moved to the North West of the Island and I was diving with EasyDive at the Le Meridien Hotel. My guide Jonathan Cesar was also a photographer, so he was happy to guide me and then leave me to my own devices once we were on the dive site. Our first port of call was a small bommie system called Emily reef.

"Why Emily?" I asked. Jonathan looked at me with a sad face and said, "Well, she was a diver and... here she drowned..." He kept this up for a few seconds before cracking up into laughter and said 'no, it is named after a ship wreck". This was going to be fun.

The visibility here was a little better and I managed to get several shots to piece together to show the reef in its entirety.

We toured the reef and bommie system for half an hour so before finding our target, a small outcrop that held three anemones and here the fun began. The first anemone we spotted was firmly 'planted' on the rock itself, complete with a resident pair of 'gasters and I was able to get some acceptable shots.

However, as anyone who has photographed clownfish in the wild will know they are tough customers and will attack the dome ports of cameras. I looked over to see Jonathan gesticulating wildly at the larger of the two that refused to sit in its host and was more interested in trying to chase his camera away.

I spotted another anemone, another H. magnifica, that had taken up residence atop a former coral outgrowth, as I headed towards it to photograph its bright red column one of the two 'gasters shot over to it and nestled into its tentacles and I also noted another to the right of me - two fish were hosting in three anemones. To add to their annoyance, every time they moved from one to another, they had to chase out a small shoal of Dascyllus trimaculatus.

All of this commotion didn't go unnoticed and within a few minutes a Lionfish had swum over to see what all the fuss was about. Now in my experience lionfish always keep a respectful distance away, but not this one, he was within inches of my face and arm, so I bid a hasty retreat, right into the sand and well, the next photo shows what happened.

After what seemed like an age the vis cleared and I looked over to see Jonathan, I'm not sure how I could tell, but he was laughing at me. The Lionfish was still hungrily eyeing up the clownfish and I realised this had played itself out before. Every time the clowns move they were at risk form predation and every time the Dascyllus were ousted they too were at risk, my presence was just giving the lionfish the distraction he needed. Either way I managed to get some good shots.

Our next dive took us to a pair of barges that were sunk in the 1980s to become artificial reefs - the afore mentioned Emily and the Water Lilly. These ships were never going to be classed as the world's greatest wreck dives but they were replete with fish including the only Anthias I saw on my entire trip and a beautiful pair of Moorish Idols.

The wrecks were surrounded by shoals of blue lined snapper and also had a few anemones with resident 'gasters, including a specimen a few inches across within a tyre. I cursed my earlier camera disaster for ruining my macro lens, this would have make a superb shot.

Later that day we moved onto the wreck of the Stellar Maru, a larger ship sunk in the 1980s that landed on its side and was later 'righted' by a cyclone and now sits on its hull as intended, but it shows the power of the ocean and why most of the corals I'd seen were of the more massive and robust species and growth patterns outside the lagoon.

The Stellar Maru is a fishkeepers' delight; various species of butterfly and angel are common place, with one large Emperor posing for photos. What I was hoping for though, was a chance to photograph Gem Tangs in the wild - another native of these parts, but this wasn't to be and Jonathan said he very rarely saw them. Other Acanthurus and many Naso species were very common and were targeted by fishermen using large traps, baited with shoreline algae. I was told that commercial fishing was heavily regulated and licensed and the guides told me they thought the pollution from agriculture and industry was more responsible for the drop in fish stocks than overfishing.

So was it worth it? Undoubtedly yes, I am one camera and one lens down, but to see species that exist no where else is always an experience to cherish, both on land and underwater. Will I ever see 'gasters available in my LFS? Not for a while I imagine, but if they were be added to a CB programme they would make a welcome addition to any stock list.

I was disappointed not to see gemmatus, but maybe I'll have to return and I must say I'm very tempted to try to reach the Chagos archipelago to photograph Amphiprion chagosensis, but that may be a more difficult proposition.

In early the 1970's, when I was just 13 or so, Cryptocaryon irritans ("marine ich") and Amyloodinium ocellatum ("marine velvet") were a bit less of a problem for my fish than they are now when I quarantine new fish as an aquarium curator. The reason was a product called Marex from the Aquatronics Corporation (they have long ceased operations). Marex was sort of a wonder drug for us back then - simply adding a single $1.99 dose protected the fish in a 50 gallon aquarium from many diseases plus it killed the unsightly algae that grew all over the tank decorations back in those days! When the company went out of business I moved on to using other products. For the past 25 years, I've been using ionic copper measured with a spectrophotometer twice a day to control marine ich and other protozoan diseases. Copper is slow to affect a cure, and the difference between a therapeutic dose and a dose harmful to some fish species is slight. Still, it seemed to be the best method for quarantining or treating active diseases in fish. Thinking back to when I was a youngster, I did some research and discovered that the active ingredient in Marex was chloroquine, and I was familiar with that drug as it was being used by other public aquariums. Acquiring some myself five years ago, I've begun incorporating it into my arsenal of aquarium fish disease treatments. A few home aquarists have begun re-exploring its uses as well, often calling it by the shorthand name of "CP" which stands for chloroquine phosphate. This article provides those aquarists with additional background information to enable them to be better able to use this "new" drug if they wish - having options is always a good.

Chemical properties

Chloroquine was developed for human medicine in the 1930's at Bayer laboratories. It was first thought to be too toxic for any practical use, but decades later, it was shown in clinical trials to have significant value as an anti-malarial drug. However, its subsequent wide-spread use allowed the malaria disease organism to become resistant to it, requiring the development of other treatments.

There are at least three forms of the drug available:

Chloroquine diphosphate (Aralen): C₁₈H₂₆ClN₃ ^. 2H₃PO₄

Chloroquine hydrochloride (Aralen HCL): C₁₈H₂₆ClN₃ ^. 2HCl

Chloroquine sulfate (Plaquenil): C₁₈H₂₆ClN₃ ^. H₂O₄S

The Chloroquine base also goes by the name; 7-chloro-4-[[4- (diethylamino)-1-methylbutyl]amino] quinolone. The most commonly available version of the drug for aquarium use is the diphosphate salt. This compound is a fine white fine powder that is readily soluble in water. In dry environments it seems to build up a static charge, and the granules tend to become airborne and then stick to nearby objects. This can create problems when weighing out small amounts of the drug, as it tends to stick to the storage container, the weighing pan as well as nearby objects. Always dissolve the prescribed amount of chloroquine in distilled water before adding it to an aquarium.

English pronunciation of the compound varies between "KLOR-oh-kwin" and "Klor-oh-KWEEN", with the former used by most aquarists, while the latter is listed on some word pronunciation web sites.

Uses and dosages

Chloroquine is typically dosed at a rate of 10 to 20 milligrams per liter (mg/l), with 15 mg/l being considered a "standard dose" (Hemdal 2006). Note: in most instances, solutions measured in "milligrams per liter" are equivalent to "parts per million" or ppm.

The 10 mg/l dose should be used as a quarantine preventative (not for active diseases), or for treating delicate species (although little is known about the sensitivity of different fish species to this medication). A dose of 15 mg/l is considered the normal dose for treating most protozoan infections, while the 20 mg/l dose would be reserved for attempting to eradicate difficult-to-treat Uronema marinum infections.

The first step in preparing to use any drug that will be added to an aquarium at a specific dose is to determine the true water volume of the aquarium. This is often less than an aquarium's advertised volume (or it could be more if there is a sump attached to the system). The most accurate means to determine the volume of an aquarium system is to measure the amount of water it takes to fill the total system, with all decorations in place. As this is usually not possible to do except when the aquarium is first filled, the following method will give accurate enough results in most instances (this method uses US volume measurements combined with metric dosages):

• Measure (in inches) the length, width and height of the water inside the aquarium from the top of the gravel layer to the water's surface, and inside the glass front to back and side to side. Multiple these three numbers to get the gross volume in cubic inches and then divide by 231 to determine the volume in gallons (there are 231 cubic inches in a US gallon).
• Deduct an estimated percentage for tank decorations. If you are unsure, the decorations in a typical marine aquarium with artificial coral and rock displace about 15% of the water volume, so you would multiply the gross volume from step 1 by 0.85
• Use the same technique to measure the volume of the gravel layer (if any), but multiply the result by 0.30, as only about 30% of the gravel layer is water, the rest of the volume is the gravel itself.
• Use the same technique to measure the volume of the sump (if any).
• Except for very large systems, the amount of water contained in the filtration system is inconsequential, but you might want to add a couple of gallons to the estimate if the tank uses a large canister filter.
• Add these measurements together to arrive at the estimated net aquarium volume in gallons.
• Once you have estimated the aquarium system volume, multiply the number of gallons by the target dose of the drug (in mg/l or parts per million). Dividing this by 266 will give the number of grams of medication that needs to be added to the water.
• Always run these calculations TWICE to ensure accuracy. If you arrive at different numbers, stop and determine where the mistake was made.

 

One grave issue when dosing medications occurs if a decimal place is lost through an error in calculation. This can result in a dose many times higher or lower than is called for. Aquarists who are not familiar with using a particular drug may not realize that the dose they have calculated is so far off. For a frame of reference, to dose 100 net gallons of aquarium water with chloroquine at 15 mg/l, you would add 5.6 grams of the drug (100 gal. * 15 mg/l / 266 = 5.639, which rounds down to 5.6 grams of chloroquine).

Home aquarists may have difficulty in measuring minute amounts of a drug to treat small tanks. Avoid guessing or trying to use volume measurements for these weights. Small electronic balances are available for relatively low cost, but may not have sufficient resolution to measure amounts of a drug in the milligram range. One trick to improve accuracy of a measurement is to make a stock solution, and then use a small quantity of that to dose the tank. The reason this works well is that home aquarists generally can measure small volumes of a liquid easier than they can weigh small amounts of a powder. For example, if you need to treat a 10 gallon aquarium with chloroquine at 10 mg/l, you would need to add 376 mg of the drug to the tank, a very small amount to try and weigh out. If you can more easily weigh out a single gram (a nice round amount), you can dissolve that into 12 teaspoons of distilled water, and then add 4 ½ teaspoon of that solution to the 10 gallon tank. For increased accuracy, you can buy a volumetric medicine dosing spoon. These can be used much like a graduated cylinder for measuring accurate amounts of a stock solution. For this example, you would add one gram of chloroquine to 100 milliliters of distilled water, and then add 37.6 ml of that stock solution to the aquarium.

Why the concern about such an accurate dosage when chloroquine has a plus or minus 33% margin of error when using the 15 mg/l dose? The reason is that there are two primary chances for error; in the tank volume calculation and when weighing of the drug itself. Two small errors may more or less cancel each other out, but if the errors are in the same direction, they are additive or subtractive and the dose you add to the aquarium could then be outside reasonable limits.

In addition to controlling protozoan parasites, chloroquine also has some use in eradicating certain metazoan (multi-celled) fish parasites. The Georgia Aquarium has used it to control turbellarian worm infestations at a dose of only 10 mg/l (Tonya Claus, personal communication). These worms have been shown to be resistant to treatment with Praziquantel and formalin, so an alternative treatment such as this is much needed.

A single dose of chloroquine at 15 mg/l was found to be effective at eradicating Aiptasia sp. glass anemones within 48 hours. In one test, no reinfestation of these pest anemones was seen in two months following treatment (personal observation). However, this method cannot be used in aquariums housing other invertebrates as this dose also eradicated algae and sponges that were growing alongside the Aiptasia sp. anemones.

In an effort to isolate the drug from sensitive invertebrates, some aquarists have administered the drug orally to their fish. Chloroquine is very bitter, and if the drug isn't masked by strong flavors in the food used to bind it with, fish will soon learn to avoid it. In addition, for oral medications to work, the fish still needs to be feeding normally, and acutely ill fish often refuse to feed. Finally, dosage is very difficult to control in oral medication for aquarium fishes. The drug must be mixed into a gelatin food binder at 6 to 10 milligrams of drug per gram of food, and then that has to be fed to the fish at a rate of around 3% of its body weight per day - and few, if any aquarists know the actual weight of their fishes.

Activated carbon has been widely reported to remove chloroquine from aquarium water at the conclusion of a treatment, but be aware that carbon has been implicated in the development of head and lateral line erosion in marine surgeonfish (Hemdal & Odum 2011). If you do decide to use carbon to remove chloroquine, it would be advisable to use a premium pelleted carbon, rinse it well with deionized water prior to use, and remove all of the carbon when finished. The amount of carbon needed to remove all of the chloroquine will be a guess. A starting point would be 4 to 6 grams of well-rinsed carbon per gallon of aquarium water, placed in a fine mesh bag and added to the aquarium's power filter for 48 hours. If the aquarium will be using delicate invertebrates at the conclusion of the treatment, it would be more prudent to change all of the water first.

There is no test kit to measure the chloroquine concentration in water as there is for many copper medications. Public aquariums and laboratories with access to a UV spectrophotometer can use it to measure chloroquine in the water directly. How this works is that at 329 nm, chloroquine in water absorbs ultraviolet light in proportion to its concentration. Using a quartz cuvette that is transparent to UV, a blank sample of untreated water is first measured. Then, a sample of that water is dosed with a serial dilution of chloroquine in the range to be treated, typically 2.5, 5, 10, 20 and 25 mg/l and the percent transmittance is measured for each sample. Once this standard trend line is graphed, the chloroquine concentration of any water sample within that range can be measured. Because other organic compounds can be present in aquarium water that may also absorb UV light, it is best to create a standard curve for each water system prior to treatment.

In one test attempting to measure the ability of carbon to remove chloroquine, a spiked sample actually showed an increase in absorbance at 329 nm after filtering through carbon for 24 hours. Since the chloroquine level couldn't have risen, it is presumed that something in the carbon dissolved into the water and that obscured the reading. However, this also made it impossible to determine if the carbon actually removed any of the chloroquine, so this aspect remains open to questioning. In a second test, 20 mg of chloroquine was dissolved in a liter of distilled water. This sample was then exposed to 4 g of rinsed activated carbon for a week. Measured at 329 nm, the sample only dropped by a calculated 5 mg/l chloroquine according to the standard curve. Since something in the carbon seems to be obscuring any chloroquine measurements, it is difficult to understand how any of the reports that carbon removes chloroquine could have been substantiated, at least by using a UV spectrophotometer.

Preliminary in vitro study

Two very basic qualitative in vitro tests were conducted to test the efficacy of chloroquine phosphate as a potential treatment against the ciliate Uronema marinum (Hemdal 2010). Uronema is a fairly common ciliate that is difficult to treat as these parasites can burrow into the fish's skin and therefore isolate themselves from many external bath treatments such as formalin, copper and hyposalinity. These informal tests show that this drug is effective at killing Uronema when it is used as a bath, but it is unknown if enough of the drug would taken up by the fish in order to raise the level in the blood to therapeutic levels.

In the first test, the body of a small parrotfish fish that had succumbed to a Uronema infection was cut in half. One section of the fish was placed in tank water, the second section was placed in tank water dosed with Chloroquine at 40 mg/l (a higher than normal dose). After six hours, the number of Uronema in the treated sample had been markedly reduced, while the numbers in the untreated sample had actually increased.

In a second test, the bodies of two green chromis that had died from acute Uronema infections were exposed to chloroquine at 35 mg/l. A marked reduction of the numbers of the ciliate was seen within three hours, and only one surviving Uronema was seen on the body of one of the fish after eight hours. Using deceased fish for these bio-assays is problematic in that there is difficulty obtaining specimens "as-needed" and room temperature tests longer than 24 hours cannot be performed as the fish flesh begins to putrefy.

Contraindications

At doses typically used to treat fish diseases, chloroquine is also toxic to many invertebrates, algae and bacteria. Seriously high ammonia levels ( > 1 mg/l NH₃) are sometimes seen a few days to a week after dosing an aquarium with chloroquine. It is unknown why this is seen in some aquariums but not others. One hypothesis is that the chloroquine has a direct antibiotic effect on the nitrifying bacteria. Another idea is that the chloroquine kills so much microscopic life in the aquarium that the beneficial bacteria are overwhelmed, and an ammonia spike develops. Most likely, it is a combination of both of these factors causing this issue. Always monitor the ammonia levels in aquariums during treatment with chloroquine. Freshwater aquariums should also be monitored for subsequent rise in nitrite levels as well.

Ultraviolet light seems to alter the chemical make-up of chloroquine in water. This is particularly a concern when UV sterilizers are employed. The UV light causes changes in the chloroquine that can turn the aquarium water a murky brown (Tiffany Adams, Shedd Aquarium, personal communication). The presumption is that the effect of the drug is also altered, so UV sterilizers (and probably ozone generators) must be turned off during treatment. Some aquarists go to the extreme of blocking all light entering the aquarium during treatment, but this is not necessary unless the aquarium is open to natural sunlight.

As mentioned, the use of chloroquine to treat malaria in humans has long been known to lose effectiveness as the Plasmodium protist that causes the disease developed a resistance to the drug. Purely speculation, but the same mechanism could cause resistance to aquarium disease-causing protists as well. If this problem ever develops, it will most likely appear in public aquariums or fish importers as they use the drug repeatedly in the same centrally filtered systems. Home aquarists are unlikely to administer the high number of treatments required to cause such a resistance to develop.
The Material Safety Data Sheet (MSDS) for chloroquine phosphate is difficult to interpret. Much of the toxicity data listed were derived from chronic exposure in humans taking the drug for control of malaria; retinal damage, nervous system disruption, and liver damage. Acute exposure of the amounts typically used in home aquariums can cause irritation to the eyes and respiratory tract. Always use gloves, eye protection and a dust mask when handling this material, and keep it away from children and pets.

The Phosphate Connection

Most, if not all of the chloroquine available for aquarium use is in the form of chloroquine diphosphate (as opposed to chloroquine hydrochloride or sulfate). This means that dosing an aquarium with this drug will also add some phosphate (PO₄) to the water when the compound dissociates as it dissolves. Theoretically, using the molecular weights of its components, chloroquine will release about 20% of its weight as PO₄ . This means that for a typical 20 mg/l dose of chloroquine, one would expect the phosphate level in the aquarium to rise by around 4 mg/l. Empirically, a series of tests on chloroquine at 20 mg/l in distilled water resulted in a concurrent rise in PO₄ of 4 to 6.1 mg/l, a bit higher than expected*. A rule of thumb might be that for any dose of chloroquine, you could expect to see a rise in phosphate levels of around 20 to 30% of the total dose of chloroquine. Therefore, a single dose of chloroquine at 10 mg/l would increase the PO₄ concentration in the water by about 2 to 3 mg/l. This is would be a major concern in reef aquaria, but as chloroquine is typically used in fish-only aquariums, or quarantine systems, the residual phosphate is less of an issue and can be reduced by water changes.

*Please note that phosphate is difficult to measure, even using a spectrophotometer, and there was a large variation in the measurements taken in these tests, with no real explanation.

Availability

The current major drawback to using chloroquine to treat fish diseases is locating a commercial source of the drug. Public aquariums, buying large quantities, have no difficulty in acquiring it from online companies at around $185 per kilogram. Hobbyists, needing much less of the drug, have not been able to find it easily available in lesser amounts - but that should be changing, now that its use has become more popular again. Until an aquarium manufacturer starts marketing it again, you may be able to acquire it from your veterinarian, or perhaps go in for a "group buy" with other hobbyists. Recent online prices for non-prescription chloroquine vary depending on the amount purchased from .185 cents per gram up to $2.40 per gram. One gram of chloroquine will dose 18 gallons of water at 15 mg/l.

Conclusion

While not a panacea or miracle drug, chloroquine is experiencing resurgence in popularity for use in fish-only aquariums and quarantine systems to treat a variety of problems ranging from Cryptocaryon to Aiptasia anemone infestations. Chloroquine remains active in aquariums for many weeks, seems to have low toxicity to fish and may be removed using activated carbon. In critical applications, treatment levels can be measured with a UV spectrophotometer, and the dose adjusted accordingly.

References

1. Hemdal, J.F. Odum, R.A. 2011. The Role of Activated Lignite Carbon in the Development of Head and Lateral Line Erosion in the Ocean Surgeonfish. North American Journal of Aquaculture 73:4, 489-492
2. Hemdal, J.F. 2010. Red Band Syndrome. Aquarium Fish International 22(1):26-30
3. -- 2009. Mortality Rates of Fishes in Captivity. Advanced Aquarist's Online Magazine. 8(12): http://www.advancedaquarist.com/2009/12/fish2
4. -- 2006. Advanced Marine Aquarium Techniques. 352pp. TFH publications, Neptune City, New Jersey

Few examples of symbiosis in the whole natural world show such a wonderful balance between giving and receiving like the mutual relationship existing between Shrimp-Gobies and their fellows Alpheid Shrimps.

Shrimp-Gobies are little fish widespread along tropical and sub-tropical seas worldwide, especially in sandy or rubble areas, where they share their 'house' (a burrow) with small prawns, commonly called snapping-shrimps.

It is quite common to observe these gobies watching the burrow entrance, in strict physical contact with the shrimp's antenna, while he approaches the surface to eliminate the material excavated from the burrow. Shrimp's eyes, used to the burrow's darkness, are almost blind out of the hole and the he could be a too-easy prey without the protection and the continuous surveillance of the goby. On the other hand, the goby is not able to dig a hole by itself, and if a burrow not well maintained would collapse in a very short time. When a danger approaches, the goby first signals it to the shrimp by flippering the caudal fin. If the danger gets worst, the goby turns rapidly escaping inside the burrow.

It has been quite a debate if we should consider the goby just like a "watchman" for the shrimp, or on the contrary the shrimp is barely a housekeeper for the goby. The truth is that both of them have built a very complex and stable relationship, where right and duties of the pair are well established and balanced: even if sometimes it's possible to observe a shrimp without his goby (or vice versa, that's it is called "facultative association", at least in some species), it's normally a temporary situation. The couple pairing is necessary for the survival of both, as life is hard alone. Natural enemies like Lizardfish, Jackfish, Sandperches and some other predators like snake eels have been observed sometimes successfully hunting Shrimp-Gobies.

It's a chicken-and-egg debate if is the goby first to find the shrimp, or the shrimp that finds the goby: the only sure thing is that they use different methods. Apparently gobies find their partners mainly using their visual ability, while chemical signals seem to have a prevalent role from the shrimp's point of view: it seems reasonable considering the poor visual ability of the little crustacean. This relationship can begin shortly after the goby settles from planktonic life, when the little fish is almost 1 cm long. When the sexual maturity is reached, normally a pair male-female of gobies shares the same burrow together with a pair of shrimps.

When the pair it's formed, the process of building the burrow starts and, depending on the substrate and on the species of shrimp, could be short and branching, or long and deep, as it has been observed sometimes in some aquariums where the shrimp decided to build his house nearby to the glass.

The activity of the pair during the day is quite intense: the shrimp keep removing material from the burrow, enlarging the house and looking for food. The goby, aside from his watchman duties, is busy in catching his food (mainly zooplankton). Most gobies just lay down on the sand waiting, while some others hover on the top of the hole. The pair activity normally is reduced in the late afternoon, and in some cases during the night the shrimp closes the burrow entrance as a further protection against night predators.

Watchman Goby

More than 130 different goby species belonging to almost 20 genera are officially already described, but probably many other are still waiting to be discovered, especially in the Coral Triangle area (Indonesia, Malaysia, Philippines an Papua New Guinea). The symbiosis has been observed with up to 30 different species of pistol-shrimps, mainly of the genus Alpheus.

The genus Amblyeleotris includes almost 40 different species, usually are the largest Shrimp-Gobies in the wild, growing up to 20 cm length in the bigger species, and with more fin rays than other genera. Even Cryptocentrus is a successful genus and it's distinguishable for the bigger head and some other anatomical features. Ctenogobiops and Vanderhorstia are quite diffused all around tropical Indo-Pacific waters, but few species have been official described until now. One genus particularly loved by aquarists, Stonogobiops, includes few species all with swim bladder that allows them to hover motionless few centimeters on the top of the burrow entrance.

Shrimpgobies in the wild feed on zooplankton mainly. Quite often a couple of gobies inhabits the same burrow, where the female lays the eggs. They are territorial fish even if the territory is not very large and in the same area it's possible to find several couples. They are not very good swimmer of course, but can be very fast.

House-maid Shrimp

All the shrimps living in association with a goby belong to the Alpheidae family (genera Alpheus or Synalpheus). They are even called "Snapping Shrimps" or "Pistol Shrimps" for their ability to produce a loud snapping sound using their larger claw. Even if they are so small, they are one of the major sources of underwater noise.

The production of this noise is one of the most amazing performances of the animal world: by snapping their claw they produce a small cavitation bubble that moves approximately 100 km/h generating a huge acoustic pressure. This bubble, producing almost 220 decibels, can also kill small fish or other animals and preys. A human eardrum ruptures a 150, just to give an idea of the power. And, unique case in the animal world, the bubble produces a small luminescence (not visible to the naked eye), called "sonoluminescence", provoked by the bubble's superficial temperature. Due the importance of the bigger claw in a snapping shrimp's life, in the case they lost it, the second claw grows to replace the lose one, and the missing limb will regenerate in a smaller claw. This amazing phenomenon is called "claw symmetry" and it has been documented only once in nature.

Snapping shrimps are socially monogamous and territorial, with females performing all parental care. Anyway, male and female partners share other duties like territorial defense, burrow construction, and foraging duties by returning food to the burrow, where both partners consume it.

 

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Biography

Francesco Ricciardi is a PhD in Marine Biology, with specialization on the impact of pollution on marine life, aquatic biodiversity and marine tropical ecology, including some studies on symbiosis ecology. Underwater Photographer and Scuba Instructor since more than 10 years, he's actually located in the island of Bali (Indonesia).

There probably are few aquarium fish that are as beautiful, interesting and distinctive as the freshwater stingrays. They are typically the center of attention in any public or private exhibitry that they are displayed in. Certain special considerations, however, must be made to properly house them, which preclude many types of aquarium systems, aquascapes and tankmates outright. Still, while they require a high level of rather specialized husbandry, the rewards for successfully maintaining these remarkable animals are great.

Several genera of freshwater stingrays appear in the ornamental fish trade. However, those of the genus Potamotrygon, the so-called river stingrays, are undoubtedly the most common. Reasons for this are many. They are strikingly handsome fishes. They reach relatively modest adult sizes. They generally accept a variety of readily available aquarium fish foods. Under the care of an experienced aquarist, long-term survivability is quite feasible. Most notably, they even can be bred and reared in captivity.

This piece discusses the classification, distribution, ecology and conservation of river stingrays; a following piece will discuss river stingray morphology, reproduction and husbandry.

Classification

The true rays and skates, Superorder Batoidea, are assigned (along with all other jawed cartilaginous fishes) to Class Chondrichthyes. They share Subclass Elasmobranchii with sharks and chimaeras. Rays account for about half of all elasmobranch species. Of the 500 or more described ray species, there are over 150 stingray species that are assigned to approximately 20 genera. Freshwater stingrays of the family Potamotrygonidae are assigned to the genera Paratrygon, Plesiotrygon, Heliotrygon and Potamotrygon. To date, as many as 20 described species are assigned to Potamotrygon. P. hystrix is recognized as the type species. Some aquarists use a P-number system (which is similar to the L-number system associated with loricariid catfishes) to classify these animals.

Below is a complete list of the currently valid names of species included in Genus Potamotrygon.

• Potamotrygon boesemani Rosa, M. R. de Carvalho & Almeida Wanderley, 2008 (Emperor ray)
• Potamotrygon brachyura (Günther, 1880) (Short-tailed river stingray)
• Potamotrygon constellata (Vaillant, 1880) (Thorny river stingray)
• Potamotrygon falkneri Castex & Maciel, 1963 (Largespot river stingray)
• Potamotrygon henlei (Castelnau, 1855) (Bigtooth river stingray)
• Potamotrygon humerosa Garman, 1913
• Potamotrygon hystrix (J. P. Müller & Henle, 1834) (Porcupine river stingray)
• Potamotrygon leopoldi Castex & Castello, 1970 (White-blotched river stingray)
• Potamotrygon magdalenae (A. H. A. Duméril, 1865) (Magdalena river stingray)
• Potamotrygon marinae Deynat, 2006
• Potamotrygon motoro (J. P. Müller & Henle, 1841) (Ocellate river stingray)
• Potamotrygon ocellata (Engelhardt, 1912) (Red-blotched river stingray)
• Potamotrygon orbignyi (Castelnau, 1855) (Smooth back river stingray)
• Potamotrygon schroederi Fernández-Yépez, 1958 (Rosette river stingray)
• Potamotrygon schuhmacheri Castex, 1964
• Potamotrygon scobina Garman, 1913 (Raspy river stingray)
• Potamotrygon signata Garman, 1913 (Parnaiba river stingray)
• Potamotrygon tatianae J. P. C. B. da Silva & M. R. de Carvalho, 2011
• Potamotrygon tigrina M. R. de Carvalho, Sabaj Pérez & Lovejoy, 2011 (Tiger ray)
• Potamotrygon yepezi Castex & Castello, 1970 (Maracaibo river stingray)

Genetic analysis of wild specimens suggests that the origin of the group can be attributed to a single colonization event. The role of hybridization in the speciation of the group, however, remains unclear. There is a considerable number of shared characteristics between species, as well as considerable variation within some species. The presently undescribed Itaituba river stingray (or P14), which evidently differs from P. henlei and P. leopoldi only in the size/number of spots, could possibly be one such variant or hybrid form. Indeed, some recent studies put into question the validity of the present taxonomic organization of these animals altogether.

Distribution/ecology

Of the many, diverse elasmobranchs, Potamotrygonidae is the sole extent family that is completely restricted to freshwater. While potamotrygonids are primarily river dwelling (or potamodromous), they are capable of exploiting a variety of freshwater habitats. Potamotrygon is native to the murky river systems of neotropical South America. This highly specialized, monophyletic group occurs mainly within a narrow geographical range spanning the Amazon River Basin. Curiously, members of this genus are found only in those rivers that drain into the Caribbean Sea or Atlantic Ocean. However, they are not found in the upper Paraná basin, the northeastern Brazilian São Francisco basin, Argentinean rivers south of the La Plata River, or northeastern and southeastern Brazilian rainforest rivers that drain into the Atlantic Ocean. Potamotrygon usually inhabits ranges that are restricted to a single river system or basin. Usually, no more than a few species (P. motoro and P. orbignyi, for example) occur in the same basin. In certain cases, a species (P. leopoldi, for example) may be restricted to a single river.

River stingrays dwell in a diverse range of freshwater environments, such as sandy lake beaches, flooded forests, and small, muddy creeks. Some species thrive under unusual environmental conditions such as very low pH or low dissolved oxygen concentrations (hence, one interesting adaptation to freshwater environments: the ability to float on the surface when bottom waters are oxygen poor).

However, river stingrays are restricted to water where salt concentrations do not exceed 3.0 ppt. Interestingly, potamotrygonid blood chemistry differs appreciably from marine and euryhaline elasmobranchs. For instance, because the rectal gland excretes little or no salt, they are incapable of retaining urea.

River stingrays tend to be more active at night, particularly while feeding. They are best described as nonspecialized predators. Wherever they occur, they generally are at the top of the food web. Adults prey mainly on fish, worms and small crustaceans, whereas juveniles prey mainly on small crustaceans and aquatic insects.

Conservation

As they typically inhabit relatively restricted ranges, potamotrygonid stingray populations are especially sensitive to harvest as well as environmental disturbances. Both indirect threats (e.g., habitat destruction due to development, mining, and damming) and direct threats (e.g., the indiscriminate killing of stingrays as pests, collection for the aquarium fish trade) have resulted in tight regulations for stingray "fisheries" as well as CITES II protection. To date, five river stingray species have been registered in the IUCN Red List as threatened.

While river stingrays are seldom fished for food, they are often taken as trawl net bycatch. They are also under significant pressure from ornamental fisheries. Owing to a high incidence of hybridization (both intentional and accidental) within captive populations--and a growing demand for "pure" lines--trade in wild-caught specimens has become quite lucrative. This has not escaped the attention of individuals who now harvest river stingrays heavily in unprotected areas just outside the borders or poach where harvest is prohibited. 20,000 specimens are legally exported from Brazil annually, with some unknown number of individuals (especially P. henlei and P. leopoldi) exported illegally. Strangely enough, another estimated 20,000 individuals are destroyed each year during "cleanups" along stretches of river beaches frequented by tourists; the waste involved in this practice should be obvious to anyone.

Commercial river stingray breeding facilities are currently operating in the United States, Germany and Southeast Asia. Fortunately, the use of PIT tagging in the trade is slowly regaining the confidence of consumers who are again relying on breeders, rather than collectors, to supply "pure stock." In fact, as breeders continue to increase production, they could potentially flood the market with captive bred product and all but neutralize the export of river stingrays from their native lands altogether. At the very least, relieving pressure on wild populations in this way could help to ensure that the existing legal harvest quotas will not be reduced, thereby keeping supply lines for wild genetics open.

Sources

1. Kuba, Michael J., Ruth A. Byrne and Gordon M. Burghardt. (2010). A new method for studying problem solving and tool use in stingrays (Potamotrygon castexi). Animal Cognition, 13(3), 507-513.
2. Toffoli, Daniel, Tomas Hrbek, Maria Lúcia Góes de Araújo, Maurício Pinto de Almeida, Patricia Charvet-Almeida. (2008). A test of the utility of DNA barcoding in the radiation of the freshwater stingray genus Potamotrygon (Potamotrygonidae, Myliobatiformes). Genetics and Molecular Biology 31(1), 1-116.
3. de Araújo, Maria, Lúcia Góes, Patricia Charvet-Almeida, Mauricio Pinto de Almeida and Henrique Pereira, Brazil. (2004). Conservation perspectives and management challenges for freshwater stingrays. Ichthyology at the Florida Museum of Natural History. 14, 10-12.
4. Charvet-Almeida, Patricia, Maria Lúcia Góes de Araújo, Ricardo S. Rosa and Getúlio Rincón. (2002). Neotropical Freshwater Stingrays: diversity and conservation status. Ichthyology at the Florida Museum of Natural History. 14, 10-12.
5. de Araújo, Maria, Lúcia Góes, Patricia Charvet-Almeida, Mauricio Pinto de Almeida and Henrique Pereira, Brazil. (2004). Conservation perspectives and management challenges for freshwater stingrays. Ichthyology at the Florida Museum of Natural History. 14, 10-12.
6. Charvet-Almeida, Patricia, Maria Lúcia Góes de Araújo, Ricardo S. Rosa and Getúlio Rincón. (2002). Neotropical Freshwater Stingrays: diversity and conservation status. Ichthyology at the Florida Museum of Natural History. 14, 1-4.
7. http://www.monsterfishkeepers.com/forums/showthread.php?t=172190
8. http://fishbase.org/summary/FamilySummary.php?ID=21
9. http://www.cites.org/common/com/ac/20/e20-inf-08.pdf
10. http://www.raylady.com/Potamotrygon

Few would argue that the Moorish idol is among the most handsome and graceful of fishes. Representations of this highly distinctive animal have served as marine iconography on everything from fine art pieces to shower curtains. It certainly has not escaped the interest (and nets) of the aquarium industry. For long it has been widely familiar even to novice aquarists. Nevertheless, it continues to have a limited presence in the trade on account of its poor record of survivability.

In all likelihood, no saltwater fish species has attracted, intrigued and frustrated aquarists like the Moorish idol. Its reputation as a delicate aquarium fish is indeed nearly as well known as its unique appearance. Somehow, this notoriety has actually elevated the regard many hobbyists have for the species; while most accordingly avoid it altogether, some find the challenge it presents to be downright irresistible. Thus, all too often, ill-informed and ill-prepared fishkeepers, armed with one trick or another, chose to learn the hard way that which so many before them have already discovered: Moorish idols are simply hard to keep. No reputable dealer (or responsible author) would assert otherwise. All of that being said, there is a considerable difference between hard to keep and impossible to keep. As a handful of capable aquarists have convincingly demonstrated, it is certainly possible to maintain Moorish idols in captivity for extended periods of time. Such cannot be accomplished with any particular trick, but rather through an uncompromising effort to:

• obtain healthy specimens.
• house them in an appropriate aquarium system.
• keep them with compatible tankmates.
• provide a varied, nutritious diet.

 

Of course, these objectives are important to successfully keep just about any aquatic animal; they are absolutely critical to successfully keep the Moorish idol. Especially concerning this species, meeting each objective will require (in the least) a practical knowledge of its natural history.

Classification / etymology

The Moorish idol (Zanclus cornutus Linnaeus, 1758) is the only extant member of the family Zanclidae (order Perciformes). Some authors place it in the family Acanthuridae (the surgeonfishes), though it differs from members of this group conspicuously in its lack of peduncular spines. It has also been placed (much more erroneously) in the family Chaetodontidae (the butterflyfishes). Fossil evidence of Eozanclus brevirhostris, an extinct relative of Z. cornutus that flourished during the Eocene epoch, serves to demonstrate a link between Z. cornutus and early acanthurids.

In reference to distinguishable features of its body form, Zanclus comes from Greek za, an augmentative particle + agklino, meaning to "bow on the back," especially like a scythe; Greek cornutus means "horned." Hence, the derivative "horned scythe."

Linnaeus first described the species in the 10th edition of his work, 'Systema Naturae' (1758) using the names Chaetodon canescens and Chaetodon cornutus. Apparently, he assigned the additional name C. canescens believing that a postlarval specimen he was working with was a different species. Meaning "hoary or turning whitish," the Latin canescens was used possibly to describe the fish's washed-out nocturnal (or dead) coloration.

In an application of international zoological nomenclature rules (the rule of 'first revision'), Cuvier, in Cuvier & Valenciennes (1831), described the genus as Zanclus and provided the type species name Z. cornutus. Günther (1876) established Z. cornutus as the valid name for the species. Nevertheless, the synonym Z. canescens is still used by some authors to this day; in some cases, both names are used in the same work.

The common name "Moorish idol" does much to convey the fish's precious, mysterious, exotic nature. It is a reference to the Moors of North Africa, who are said to believe that the fish can bring happiness to those who dwell near it.

Distribution / ecology

Z. cornutuscan be found (often in great abundance) across an extensive natural range. It is generally assumed that its wide distribution can be attributed at least in part to an unusually long, pelagic drifting phase during its larval development. It occurs throughout the Indo-Pacific and eastern Pacific oceans, with the notable exception of the Red Sea and Persian Gulf regions. It has been reported in the western Pacific from Kominato, Japan down to Lord Howe Island, and in the eastern Pacific from the southern Gulf of California down to Peru. Interestingly, it was reported near Pompano Beach, Florida in 2001--quite plausibly a consequence of aquarium specimen introductions.

Z. cornutusis rather adaptable, inhabiting a variety of hard-bottomed habitats from seaward reefs to murky harbors. It occupies a depth range of 3-182 m. It is a roving grazer that is frequently found in pairs. However, sizeable shoals can amass in areas that support an abundance of sponge, tunicates and other benthic invertebrates upon which it feeds. The author has observed the species in presumably brackish water near a large drainpipe, foraging amidst trash in surprisingly close proximity to feral tilapia.

Morphology

Z. cornutusis characterized by a strongly compressed, highly elevated, discoid body. It reaches a maximum body length of 22 cm. It has a slender, protruding, tubular snout and a diminutive mouth lined with long, bristle-like teeth. Thickened bones in its forehead develop with age into a prominent horn-like structure that projects from just above the eyes. The preopercle and caudal peduncle are unarmed. It has 6-7 dorsal spines, 39-43 dorsal soft rays, 3 anal spines and 31-37 anal soft rays. The elongated dorsal spines form a highly distinctive filament.

Its base color is white. The tip of the upper jaw is black. Most of the lower jaw is black. A bright orange patch that is outlined in black covers the top of the snout. A wide, vertical black band runs from the first dorsal spine to the ventrals. Two thin, curvilinear bluish lines run over the first black band from the origin of the ventrals to the front of the dorsal fin and from the abdomen to the origin of the dorsal fin. A third, but less distinct, bluish line runs up and back from the eye. A second vertical black band runs from the dorsal to ventral rays, widening ventrally. A thin, vertical white line runs along the posterior of the second black band. A bright yellow-orange patch extends from the caudle region where it is bordered by a thin white band, to the mid-body where it fades into the white base color. The caudal fin is black, and is edged in white.

Husbandry

The Moorish idol has proven itself to be quite delicate in the aquarium environment. This is particularly so during the period of adjustment that follows capture, transport and holding (which often precedes yet more transport and holding). Regarding this species, with few exceptions, a compromised specimen is as good as dead.

Sadly, a rather large number of recently imported individuals are seriously compromised due to shipping stress. Consequently, it is incumbent upon hobbyists (at least those that hope for the slightest chance of success with this fish) to acquire specimens from the best available sources. While careful handling must be employed throughout the entire supply line, it seems to be especially important that specimens are shipped individually in oversized bags. Specimens harvested from the eastern Pacific are said to adapt more easily to captivity (perhaps only because of the shorter shipping route). Generally, younger individuals are somewhat more tolerant of shipping stress. Further, younger individuals generally are more tolerant of acclimation stress and are better suited to captivity.

Specimens should be held by the dealer and personally observed by the buyer for weeks before purchase. This is not a species that should be purchased online (even some online venders that offer them unequivocally say so). Because of the risk (if not high level of care) involved in holding this fish, some retailers might avoid quarantining specimens prior to sale; in this case, one does best to avoid them. It is advisable to obtain specimens from dealers who will not only quarantine for 2 weeks or more, but will also be willing to demonstrate that the animal is feeding well.

Transport time from the dealer to the home aquarium should be as short as possible. All tank lights should be shut off for the remainder of the day. Whatever acclimation method is used, it should be smooth and gentle. Then, the animal should be left alone; while new acquisitions should be monitored periodically, one shouldn't cause them any undo stress by skulking at the front of the tank all evening.

The typical reef aquarium set-up should be adequate to house Z. cornutus provided that it is very large (i.e., 200 gallons or more) and completely mature, and that excellent water quality is maintained. An abundance of rockwork (albeit with long, unobstructed swim paths) will be appreciated.

Healthy live rock will often abound with organisms that can provide a source of nourishment for the new fish. If conventional prepared foods are refused, clam or mussel on the half shell may be accepted (remove uneaten portions nightly). In the proper environment, Z. cornutus can be trained to eat flake foods from its keeper's hand in as little as a couple of weeks. While it is indeed often challenging to get newly imported Z. cornutus to begin feeding, it should here be emphasized that the long-term health of this animal depends greatly upon having a properly balanced diet. Z. cornutus is not herbivorous as many once believed (perchance because of its resemblance to acanthurids); while it may be worthwhile to regularly offer it certain plant-based foods (e.g., nori), a highly varied fare that includes sponge (often found in frozen marine angelfish foods) is more appropriate for this omnivore.

Tankmates for the Moorish idol must be selected judiciously. As fragile as it might seem to be, this fish can be a real menace to any others that dare to get in its way. It can be especially aggressive toward its own kind; while there may be real benefits to keeping this fish in pairs, the likelihood of conspecific aggression is far too great to suggest housing more than one individual per tank. All the same, it can be a target for pugnacious tankmates. Fin nippers (e.g., some damsels and wrasses) may find its filamentous dorsal fin impossible to ignore. Bullies and tyrants (e.g., triggerfish) may be endlessly at odds with it on account of its apparent lack of submissiveness. Highly territorial fish (e.g., tomato clownfish) may constantly batter it as it repeatedly wanders--grazing--across their turf. Any tankmate that exhibits even the slightest threat to a Moorish idol should be removed promptly.

Conclusion

Many aquarium hobby authors have written about this animal in the past. Most tend to strongly dissuade aquarists from attempting to keep the species. The typical argument for this position evidently is an ethical one, drawing attention to the fact (and it is a fact) that (at present) few Moorish idols collected for the aquarium industry survive the first few weeks of captivity. In point of fact, this fish is quite abundant in the wild and has an unusually wide distribution. If one were to make an argument from the position of a conservationist, it certainly could be said that the impact of collecting this fish is far lesser than many other commonly kept--but naturally uncommon--fishes, regardless of captive survivability.

Few would deny that the Moorish idol is an amazing animal. Nevertheless, owing to repeated failures reported by others in the hobby, most aquarists elect not to acquire them. Considering the relatively great number of resources that are required to successfully keep them, this is quite understandable. Such is a case wherein an entire aquarium system must be built around a sole occupant. One makes no overstatement in saying that this is a species for the advanced aquarist. Still, in consideration of all of the technological and methodological refinements taking place in the hobby, there is every reason to conclude that the Moorish idol will yet become a staple of the ornamental fish trade. This will only be accomplished when distributors and retailers--and then, by extension, hobbyists--recognize that success with this species cannot be had on the cheap. They will find that obtaining strong, young specimens, housing them in a habitable living space, providing them with an appropriate diet and keeping them with suitable tankmates actually works. Moreover, they very likely will find that the considerable effort and investment is entirely worth it.

When a fishing guide takes you out and you don't catch any fish, he may say "Gee, you should have been here last week, they were jumping into the boat." Yeah, right. When a dive master takes you diving and you come up ask where the coral reef is, she may say, "Gee, you should have been here 40 years ago; it was healthy and beautiful with coral growth and tropical fish all over the place." And so it was. And I was there also. Coral heads were massive, great stands of elkhorn coral reached for the surface and the shallow reefs were topped with extensive growths of fire coral, Millepora complanata. All of these corals had different species of fish and invertebrates that live to a greater or lesser extent within the special environment that that species of coral creates. Food, shelter, reproductive substrates-the coral provide the special environmental conditions that helped that species survive in the "eat or be eaten" world of a coral reef. And it was, and still is, one of the most wondrous environments on Earth.

The company I started in 1973, Aqualife Research Corporation, moved to Marathon in the Florida Keys in late 1974 and I had the great opportunity to live, work, and dive in the Florida Key for ten years. Forrest joined me in, I think it was 1978, and we worked together until 1984 on the culture of clownfish, gobies, Atlantic angelfish, and many other species of reef fish, including the yellowtail reef fish, Microspathodon chrysurus. The juveniles of this species carried the common name of jewelfish at that time because of the brilliant iridescent blue spots that covered the body. These spots disappear as the fish attains the adult coloration of a drab dark brown body and bright yellow tail. Despite their aggressive nature, their constant movement and bright coloration made them a popular fish for marine aquariums at the time. They are a good species for reef tanks if kept one per tank.

Jewelfish lived in the fire coral reefs, they fed on algae and invertebrates that occupied these reefs, and they laid their eggs on the dead blades of the fire coral. In fact I seldom saw yellowtail reef fish except with a growth of fire coral, however small, right near them. I remember back in the mid 70s, I would hover at the edge of the fire coral reef and look over the relatively flat surface of the reef. After a while I would see male jewelfish in specific areas scattered widely over the reef popping up and flashing, dropping down into the reef and moments later popping back up, and repeating this behavior over and over again. They were tending to their nest of eggs on fire coral blades and trying to attract a female to stop by and drop off a few eggs, maybe 400 or so, to enlarge the nest that the male was tending and guarding.

I recall the first time I checked this out and found a large nest of eggs on a dead blade of fire coral. I hit the top of the blade breaking it off near the bottom. It was about 8 inches long and had more than a thousand eggs, the results of several spawns all over one side. I picked it and got very excited when I realized that I had in my hand potentially $50,000 worth of juvenile jewelfish, if I could only rear them. (But I knew then, as now, that flooding the market with one species, leads to very much lower prices and excessive unsold inventory.) But still it was certainly worth it to rear some of them.

There was considerable interest and competition in the very early days of marine fish culture and we played our cards pretty close to our vest in those days. Thus the article below from the May 1981 issue of Freshwater and Marine Aquarium Magazine (price $1.50) did not provide many details as to exactly how we reared them. But the secret was, of course, copepods from wild plankton as a first food. Suspending the blades of fire coral with their nests of jewelfish eggs in a large larvae rearing tank with a heavy flow from an air stone release underneath them was all it took to keep them alive during development and stimulate hatching when the embryos were ready.

Back in those days, rearing marine tropical fish was a quixotic exercise of producing an expensive cultured fish that competed with an inexpensive wild caught fish in a market that was highly price competitive. But still, the promise of what could be, and what would probably be, drove adventurous souls like Forrest and me to invest more of ourselves into a culture that really didn't make a lot of economic sense at the time. But some dreams never die…

Unfortunately, however, the coral reefs, at least what they were in 1970s and early 80s, did die, or at least greatly diminish. Those vast expanses of fire coral that topped the reefs are gone, and so also the yellowtail reef fish and their stunningly beautiful jewelfish juveniles are now very hard to find. Florida's coral reefs have declined for many reasons: pollution, storms, overfishing, over visitation, and disease of both corals and invertebrates. Perhaps the most critical loss of biodiversity was the almost total annihilation of the keystone herbivore of the Atlantic coral reefs, the long-spined sea urchin, Diadema antillarum, in a great plague that swept from the Panama Canal through this great oceanic region all the way to Bermuda in the space of 13 months in 1983. Within weeks macro algae began to overtake the Atlantic coral reefs and this is still the case today. These urchins have not recovered, their ecological function of herbivory is still absent and the reefs continue to decline. But now we can culture these difficult urchins, and after six years of effort I am close to completion of a functional technology for small scale urchin larvae culture, and I hope that this will stimulate more effort to restore this keystone herbivore to Atlantic coral reefs. Then perhaps the fire coral reefs and the jewelfish will return.

- Martin Moe

 

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Spawning the Jewels of the Reef

Freshwater and Marine Aquarium magazine, May 1981
By Martin A. Moe & Forrest A. Young
Aqualife Research Corporation

The yellow-tailed damselfish, Microspathodon chrysurus, or marine jewelfish as it is known in the hobby, is one of the hardiest and most colorful of the Atlantic damselfish. Juveniles exhibit a striking coloration of iridescent neon blue spots against a midnight blue background. This fades in intensity as the fish matures and only a few small blue spots remain on the drab, dark brown adult. Also, the color of the caudal fin changes from clear in the juvenile to a bright yellow on the adult, hence the origin of the accepted common name.

In nature, adult and juvenile jewelfish arc found almost exclusively among the flat, branching growths of fire coral, principally Millepora complanata. The fire coral affords the jewelfish protection from predators, reproductive sites, and even food since stomach contents are composed of algae and detritus common to fire coral reefs as well as elements of the fire coral itself. Ciardelli (1967) examined stomach contents of juvenile jewelfish and found a variety of vegetable and animal matter including nematocysts (stinging cells) that apparently were from Millepora. He feels that the ingestion of fire coral by juvenile jewelfish may explain their close relationship with the shallow fire coral reefs. Unlike other damselfish in the same environment, Randall ( 1967) reports that jewelfish were never observed feeding on planktonic organisms, but restricted their diet to benthic algae with a small amount of animal matter. He also describes cleaning behavior, removal of ectoparasites by juvenile jewelfish from large grey angelfish. Emery (1968) reports that benthic animals are important in the diet of the juveniles, including coral polyps and sponge, and that adults gradually switch to almost exclusively benthic algae.

The association of jewelfish with fire coral is so exclusive that we consider it a form of commensalism. This association is not as obvious as the spectacular commensalism of clownfish, Amphiprion sp., with anemones, but seems to be almost as obligate to the fish. It is extremely rare to find a jewelfish without at least a small growth of fire coral in the immediate environment. Further observation and ecological analysis of this association is needed to clarify the relationship between fire coral and jewelfish.

Jewelfish are beautiful and hardy and. although they are very aggressive toward others of their species, they are good solitary aquarium fish and are an excellent prospect for commercial culture.

Aqualife Research Corporation first reared jewelfish into large juveniles in mid 1976 and developed the techniques for large scale culture in late 1978. Almost 1000 individuals were reared in a single tank during this period, so tank reared jewelfish should soon be available to the hobby. Jewelfish, like other pomacentrids such as clownfish and damselfish, are demersal spawners and adhere their eggs to coral structures near the top of the reefs. Each species of damselfish has a particular place and substrate favored for nest building. Jewelfish eggs are much smaller than clownfish eggs and, like clownfish eggs, are attached at one end to the spawning site. The nests are composed of tiny, I mm diameter elliptical eggs densely packed on a coral substrate. There is an average of about 1,150 eggs per square inch of nest, and one nest with eggs in various stages of development may easily cover 20 to 80 square inches, a total of 23,000 to 92,000 jewelfish eggs on each spawning site. The eggs are translucent with a pinkish cast when newly laid and become darker as the embryo develops and hatching time approaches. The eyes are fully developed at hatching and are the most noticeable feature of the late stage embryo and early hatchling. The time from spawning to hatching is about 3 days at 80 F (27 C) and hatching usually occurs at night.

The newly hatched larvae are so small, less than l/16" long, and so slight and transparent that they are almost invisible. Those that peer into a tank of newly hatched jewelfish for the first time are incredulous that they cannot see a one of the 15,000 fish that are swimming about in the tank. However, a little searching soon reveals the presence of the diminutive larvae. One newspaper reporter was sure that he had drunk water with more critters in it than he could see in a tank of larval jewelfish.

Jewelfish larvae are much smaller than clownfish larvae and appear very similar to larval angelfish to the unpracticed eye. Some species of marine fish, such as the neon goby, metamorphose very quickly from larval to juvenile coloration and behavior patterns. This change to the juvenile characteristics occurs actually overnight in some instances, although most species require a few days to make the complete transformation. Other species, like the jewelfish, go through a prolonged period of gradual change and the juvenile characteristics are acquired very slowly. The post larval period is passed in the form of a creature adapted to the pelagic environment rather than one living secretively among the bottom growths.

The larval period for jewelfish extends to 4 weeks and the post larval period may take an additional 3 to 4 weeks before juvenile form and color are attained. The total length of the fish exceeds 1/2" before the Post larval period is complete. The most obvious structural development of the larval jewelfish is the greatly enlarged pectoral fins. During this early period, the pectoral fins extend posteriorly to almost the caudal fin and spread outward a distance equal to about the depth of the body. These large laterally spread fins greatly increase the horizontal surface area of the fish, an adaptation that provides support and mobility in the pelagic environment. These pectoral fins are always spread and give the diminutive fish the appearance of flying through the water. ln fact, they look for all the world like miniature delta wing aircraft pursuing some important mission as they cruise tirelessly throughout the tank. They pause only to sight on and strike at food organisms.

There is a price that must be paid for this extraordinary larval mobility and restless behavior. Some other species, such as angelfish and reef drum, (jackknife fish) have slow moving sedentary larvae that seem to expend their energy only at the moment of striking at the prey organism. These larvae grow much faster than jewelfish and enter the benthic juvenile stage in only 2 to 3 weeks, less than half the larval period of jewelfish. Of course, tank reared marine fish larvae experience an unnatural environment and behavior and growth cannot be assumed to be exactly the same as wild fish, although parallels certainly exist.

Apparently, jewelfish require fire coral reefs for survival in the wild, and this type of habitat, while not at all a rare kind of reef formation; it still does not cover broad expanses like grass flats or the soft coral - hard rubble bottoms. A journey of many miles might be required of the tiny post larval fish before it encounters a fire coral formation. We consider it quite possible that the extensive pectoral fin development, active swimming mode, and the prolonged period of larval and post larval stages are adaptations that provide young jewelfish the means of finding the relatively restricted type of habitat required for survival. Jewelfish are distributed on fire coral reefs from Florida to Brazil and the extended duration and mobility of the early stages must enhance such wide distribution to a restricted habitat. The energy expended in the larval stage slows growth and prolongs the dangerous pelagic period, but these disadvantages are apparently compensated by the ability to find the fire coral reefs.

As mentioned above, juvenile jewelfish feed mainly on sponge, algae, hydroids, isopods, and copepods so they adapt well to the typical aquarium diet. Since adults feed almost exclusively on benthic algae, a diet rich in vegetable matter is suggested as they mature. They take a wide variety of foods including live or frozen brine shrimp, flake foods and finely chopped shrimp.

Jewelfish make an excellent addition to a community tank. They are impressively colorful, are very active and often engage in transport of stones and objects from their home area. They may also show cleaning behavior on the larger fish in the tank. Unless the tank is quite large, however, only one jewelfish should be kept per tank because they are highly territorial and eventually the dominant fish will destroy his few unfortunate brethren. Aggressiveness toward others of their kind is not restricted to jewelfish, although they are quite good at it. Many coral reef fish are strongly territorial and will drive cognates that compete for food and shelter away from their premises. The weaker fish is only too happy to flee and find his own piece of the rock, but containment in 4 glass walls with his adversary soon leads to his demise. On the other hand, the presence of many small fish of the same species in the same tank, in this case, jewelfish, seems to diffuse their aggression and 30, 50, 100 or more can coexist and grow in a relatively small contained area. Otherwise, they would be most difficult to rear in large numbers to aquarium size. Aqualife Research Corporation has already made a few shipments of tank reared jewelfish to various dealers and, hopefully, many more will be available in the near future.

References

1. Ciardelli. A. 1967. The Anatomy of the Feeding Mechanism and the Food Habits of Microspathodon crysurus (Pisces: Pomacentridae). Bull. Of Marine Sci. Vol. 17. No. 4. PP 845-883.
2. Emery. A.R. 1968. Comparative Ecology of Damselfishes (Pisces: Pomacentridae ) at Alligator Reef. Florida Kevs Dissertation, University of Miami. Coral Gables, Florida, 258 Pages.
3. Randall, J. E., 1967, Food Habits of Reef Fishes of the West Indies. Studies in Tropical Oceanography, No.5. pp. 665-847.

One could scarcely refer to the Molly Miller blenny as an "ornamental fish." To be sure, it is one of the most hideous animals that an aquarist's money can buy. With its bulbous, bony head, huge eyes and a crown of bristlelike appendages, it bears the visage of something out of a Dr. Seusian nightmare. In lieu of the bright hues and gaudy patterns characteristic of so many other coral reef fishes, it is colored only with blotchy patches of drab browns, greens and grays. Lacking a well-developed swim bladder, it more or less lays on the bottom, clumsily scooting about in a most ungraceful manner. Really, as far as outward appearances go, its only saving grace is the sad consolation of being (at least to some fishkeepers) so ugly that it is cute.

That, of course, is not much of a consolation. Actually, this species would have negligible value in the aquarium fish trade (apart from the few peculiar fishkeepers that always seem to love the ugliest creatures) if it were not for a couple very important attributes.

While it may not be the best looking fish out there, the Molly Miller blenny does possess an abundance of something aquarists universally refer to as "personality." The antics of this intelligent, excitable and oftentimes scrappy animal are well known--indeed celebrated--among those who have kept them.

All of that being said, the Molly Miller blenny might best be described as a "utility fish." This not-so-fussy eater has earned a reputation as an effective aquarium scavenger; it is known to feed on nuisance algae and detritus, and is widely reputed to feed on cyanobacteria and Aiptasia spp. sea anemones. If even half of these reports hold up to truth, the Molly Miller blenny could truly be the preeminent clean-up critter of the marine aquarium fish trade. To note, it may be the first fish species to be commercially tank bred for this purpose.

The Molly Miller blenny is not particularly difficult to maintain in captivity; actually, there are few marine fish species that are as amendable to aquarium conditions. This can be attributed largely to its various adaptations for subsistence in harsh, unstable environments.

Natural history of the Molly Miller blenny

Range and habitat

The Molly Miller blenny (Scartella cristata Linnaeus, 1758) has an extraordinarily wide distribution. It occurs in rocky or coral reefs of the Northwest Pacific Ocean (Japan and Taiwan), the Western Atlantic Ocean (from Florida to Brazil), the Eastern Atlantic Ocean (from Mauritania and the Canary Islands to South Africa), and the Mediterranean Ocean (from Spain to Greece). While it is found in temperate, subtropical and tropical environments, it appears to fare best in warmer climes; indeed, global warming has been implicated as the cause of its growing presence in Southern Europe.

S. cristata usually inhabits very shallow waters, from tide pools down to ~10 m (i.e., the upper photic zone). However, maximal population densities (comprised mainly of small and intermediate size classes) occur at ~2-4 m depth. In general, its abundance sharply decreases with increasing depth.

Subsequent to post-larval settlement, S. cristata is non-migratory. It is primarily benthic. It favors areas that feature hiding places in the form of stone crevices, bioconcretions (abandoned snail shells, barnacle tests, etc.) or fronds of algae. Its dull coloration and dappled pattern serve as camouflage in these environments. Observations of grow-out stock at Sustainable Aquatics suggest that it can change coloration to match different substrata.

Where suitable substrate cover is ample, it typically reaches population densities of 0.4 to 0.9 individuals/m². Still, it has been observed in prime habitat at densities as astonishingly high as 9.6 individuals/m², accounting for more biomass than that of all other resident fish species combined.

Diet and feeding behavior

S. cristata exerts an enormous influence on the trophodynamics of the habitats in which it occurs. It feeds heavily on epilithic (especially filamentous) algae; nevertheless, it is best regarded as an omnivore, rather than an herbivore, for the reason that in the course of grazing it ingests a very wide variety of items included in the epilithic algal matrix (e.g., detritus and microorganisms). Further, it may target certain small sessile invertebrates (e.g., Aiptasia spp. anemones). It has even been observed feeding on fish carrion. In one gut content analysis, 41 different food items could be identified.

S. cristata feeds mainly during the day. Its feeding activity increases steadily throughout the morning hours, leveling off in the early afternoon, and then sharply decreasing until cessation at dusk. Bite frequency rises and falls with temperature. Season and location have been found to influence its diet and feeding patterns, indicating a high level of trophic versatility. The diet of subjects examined in one study varied, depending upon site and time of year, from 25-55% algae and from 35-62% detritus.

Development and reproduction

The basic adult morphology of S. cristata is quite characteristic of the Blenniidae. It has a compressed, elongated body. It lacks scales. It has large, well-developed pectoral fins, a long, continuous dorsal fin and reduced pelvic fins. It is a smallish fish, reaching a maximum length of approximately 12 cm (though they typically reach only 10 cm).

Larvae are relatively large, hatching at about 3 mm and undergoing metamorphosis at 10-11 mm. Settlement occurs around 30 days post hatch at 11-18 mm. Prior to settlement, the head and pectoral fins are heavily pigmented, while trunk pigmentation does not extend laterally far beyond the mid-body. Highly reflective blue-green pigments highlight the eyes dorsally. Consequently, when viewed from above against a dark bottom, larvae have the curious appearance of tiny flies. Little original pectoral fin pigmentation is evident in recently settled individuals. Though its size gap at settlement is rather narrow (~1.5 mm difference), significant discrepancies of size among juveniles is common even among individuals from the same brood.

Sexual dimorphism is evident shortly after settlement. While the first anal spine is clearly visible in males, it is inconspicuous in females. At >15mm, the urogenital opening forms a papilla in males but is covered by a fleshy hood in females. However, sexual dimorphism is much more evident with further maturity. Males typically become darker, larger and more slender, have a fuller, more continuous dorsal fin, and develop a more conspicuous nuchal crest. Breeding males have fleshy lateral extensions at the tips of the anal fin rays and bear spatulate pads on the first-two anal spines.

Functional sexual maturity may be reached in as little as 18 weeks. Some individuals (particularly breeding males) may establish territories and defend them with great determination. Upon securing an acceptable nest site, breeding males engage in conspicuous swimming movements to attract the attention of females. An interested female follows the male into the shelter for a brief inspection of the nest site. If satisfied, she will back in and begin depositing eggs on the shelter walls. If there is enough space within the shelter, the male will immediately fertilize the eggs as they are laid.

Each clutch consists of around a few hundred eggs; however, males are capable of tending nests that include multiple clutches from different females, and so may brood a thousand or more eggs at a time. Data gathered from a survey of one Floridian population suggest that an average of 5.5 females contribute to each nest.

Individual nests often contain clutches that have been fertilized by multiple males. Surreptitious fertilizations of "bourgeois" male nests by "sneaker" males are rather common among Molly Miller blennies; indeed, this species exhibits some of the highest frequencies of cuckoldry of all nest-tending fishes. Data from the above-mentioned survey indicate that over 12% of progeny may be sired in this manner.

Eggs hatch in the evening, usually on Day 8 at 78°F. There is no parental guardianship of the larvae. Newly hatched larvae are carried by outgoing currents to open water, where they almost immediately begin feeding on small zooplankton.

Aquarium husbandry

As it is adapted to the ever-fluctuating conditions of the intertidal zone, the Molly Miller blenny makes for an exceptionally resilient aquarium fish. Even the passably informed novice hobbyist should have little trouble successfully maintaining this animal in captivity. It can be properly housed in most types/sizes of tank. Particularly if multiple specimens are housed together, ample living space will of course be appreciated. However, maximal stocking density will be determined mainly by number of available hiding places, rather than tank size.

To say the least, feeding Molly Miller blennies is uncomplicated. While there are few, if any, reports of Molly Miller blennies targeting desirable aquarium animals, it is worth noting that they can potentially disturb certain creatures (e.g., tridacnid clams) by their intensive grazing. They will accept virtually any kind of aquarium food that they are presented with.

More notably, they have a taste for items commonly encountered by aquarists as various pests and plagues. Their propensity for herbivory and detritivory is above dispute. Interestingly, it may be possible to use them to control Aiptasia.

A simple experiment performed at Sustainable Aquatics has demonstrated the Molly Miller blenny's appetite for Aiptasia. Two cubicles in a large, recirculating system were emptied of fish. Each cubicle contained a similarly sized population of Aiptasia and red microalgae (unidentified benthic rhodophyte), as well as an equivalent amount of detritus. A tank bred, four-month-old S. cristata specimen was placed into one of the two cubicles. The fish did not receive supplemental feedings throughout the trial. By Day 2, there was a marked decrease in Aiptasia and algae populations as well as a reduction in the amount of detritus in the cubicle containing the fish; no changes were observed in the adjacent cubicle. By Day 10, much of the algae, most of the detritus and all of the Aiptasia had been eliminated. The fish was transferred to the adjacent cubicle after 10 days. Over the next 10 days, a very similar pattern was observed in the cubicle containing the fish; during this same time, no Aiptasia, some algae, and significant amounts of detritus reemerged in the vacated cubicle. While the results of this experiment do not conclusively prove any of the aforementioned claims circulating within the hobby, they do suggest that the presence of S. cristata can suppress proliferation of microalgae and Aiptasia, as well as reduce detritus accumulation.

Captive breeding of the Molly Miller blenny is possible, though not easy. While it spawns readily, its larvae are fickle and demand a rather high level of care; even well practiced fish breeder Dr. Matthew Wittenrich has described its larviculture as challenging. One major impediment to the commercial scale production of this species is the relatively large amount space required for grow-out; this aggressively territorial fish will begin to suffer from crowding at only a couple months of age in the typically bare, unsheltered culture environment. And, ironically, they can eat a production facility out of business.

Still, the culture of Molly Miller blennies for the trade is a worthwhile endeavor, for it presents a more sustainable alternative to any wild-caught herbivore, detritivore or Aiptasia-eater.

Conclusion

By most standards, the Molly Miller blenny is a spectacularly ugly little fish. Whatever it lacks in physical attractiveness, however, is more than remunerated with character. In addition to being fairly interesting to observe and remarkably hardy, it has proven itself to be useful for cleanup and control of various nuisance organisms. Hence, while it might not be a particularly "ornamental" fish, its mere presence can--by virtue of its unusual feeding habits--help contribute significantly to the beauty of display aquaria. The recent availability of tank bred specimens will almost certainly increase its appeal among those aquarists that favor cultured livestock.

Kenneth Wingerter
Process Biologist
Sustainable Aquatics
110 West Old Andrew Johnson Hwy
Jefferson City, TN 37760
ken@sustainableaquatics.com

 

References

1. Nieder, Jurgen, Gabriele La Mesa and Marino Vacchi. 2000. Blenniidae along the Italian coasts of the Ligurian and the Tyrrhenian Sea: community structure and new records of Scartella cristata for Northern Italy. Cybium 24(4): 359-369.
2. Ditty, J. G., R. F. Shaw and L. A. Fuiman. 2005. Larval development of five blenny (Teleostei: Blenniidae) from the western central North Atlantic, with a synopsis of blennioid family characters. Journal of Fish Biology 66: 1261-1284.
3. Almada, Vitor C. and Ricardo Serrao Santos. 1995. Parental care in the rocky intertidal: a case study of adaptation and exaptation in Mediterranean and Atlantic blennies. Reviews in Fish Biology and Fisheries 5: 23-37.
4. Berry, P. F., R. P. van der Elst, P. Hanekom, C. S. W. Joubert and M. J. Smale. 1982. Density and biomass of the ichthyofauna of a Natal littoral reef. Marine Ecology Progress Series 10: 49-55.
5. Topolski, Marek F. 2001. Vertical distribution, size structure, and habitat association of four Blennidae species on gas platforms in the northcentral Gulf of Mexico. Master's thesis. Auburn University, Auburn, Alabama.
6. Mendez, T. C., R. C. Villac and C. E. L. Ferreira. 2009. Diet and trophic plasticity of an herbivorous blenny Scartella cristata of subtropical rocky shores. Journal of Fish Biology 75: 1816-1830.
7. Nieder, J. 1997. Seasonal variation in feeding patterns and food niche overlap in the Mediterranean blennies Scartella cristata, Parablennius pilicornis and Lipophrys trigloides (Pisces: Blenniidae). Marine Ecology 18(3): 227-237.
8. Mackiewicz, Mark, Brady A. Porter, Elizabeth E. Dakin and John C. Avise. 2005. Cuckoldry rates in the Molly Miller (Scartella cristata; Blenniidae), a hole-nesting marine fish with alternative reproductive tactics. Marine Biology 148: 213-221.
9. Thresher, Dr. R. E. 1984. Reproduction in Reef Fishes. T.F.H. Publications, Inc.
10. http://www.reefcentral.com/forums/showthread.php?s=f2367f34d6d3da3b011e67c64232d976&postid=7644128

Many hobbyists dream of tropical locations in far distant places. They often want to recreate that sense of beauty with their aquariums. However, what they often fail to realize is that tropical beauty and thriving reef systems may not be all that far from home. The Tropical West Atlantic is filled with beautiful sea creatures and an Atlantic Biotope can make for a stunning home aquarium. These aquariums are often referred to as Atlantic Tanks or Caribbean Biotopes.

The Tropical Western Atlantic

The Tropical Western Atlantic is a region that encompasses the waters from Northern Brazil, up through the lesser and greater Antilles, the gulf of Mexico, the Florida Keys, Florida, and up towards the Georgia Carolina coastlines. The corals in these areas are beautiful, the fish are stunning, and for hobbyists in the US they are right here in our backyards. Not all animals are found in all areas of the Tropical Western Atlantic, but those common to the US shores are readily available to the hobby. This large area of natural reef habitat is often overlooked and underappreciated in the hobby.

Atlantic Corals

One of the most unfortunate aspects of keeping Atlantic systems is the governmental restrictions on corals. Stony corals (from the Scleractinia) are very rare in the hobby, because they can not be collected for the aquarium trade. These corals are amazing animals creating huge amounts (as in hundreds of square miles) of reef structure throughout the area. In addition, many other "corals" are frequently harvested and serve as great animals for the home aquarium. All sorts of mushroom anemones (Ricordea species) and Gorgonia and zoanthids are very common in the Atlantic. They all make fantastic inhabitants for captive systems and are truly an overlooked addition to a reef aquarium. Atlantic aquascapes are often usually very colorful, full of movement, and unique in their rare appearance in the hobby.

Some of the stationary invertebrates available in the hobby make wonderful inhabitants for home aquaria. The design, health, and structure of the home aquascape is created by using stationary invertebrates. In addition to the corals, these animals are the living structure for reef habitats.

• Mushroom Corallimorphs
• Hydroids
• Zoanthids
• Bryozoan
• Anemones
• Sponge
• Feather Worms
• Barnacles
• Scallops and Clams
• Tunicates

Popularity In the Hobby, from color → size → groups

Historically the popular fishes of the Atlantic were those with lots of color. The motto for collectors was "color sells" as they tried to collect the most colorful of the fish in the waters. That has shifted during the last few years with the rise in popularity of nano aquariums. Currently, small diminutive fishes are the popular choices for livestock. Even the most colorful of the angelfish are no longer in high demand. Small blennies and gobies are now the aim for collectors. Recent trends and advanced hobbyists may be shifting that trend again, with a growing demand for pairs of fishes, harems, schools, and unique specimens.

Atlantic Fishes

This is one area where abundance, variety, color, size, and everything else is at your fingertips. The Atlantic fishes are bold, beautiful, interesting, and often times serve as the highlight in a reef aquarium. What is even more amazing is that they are readily available to home hobbyists. Many local pet stores are unaware of the great market that exists for Atlantic fish, they may also be unfamiliar with what fish are available, and they don't regularly carry these fish. This is all very unfortunate given the gems that are available. Lucky for home hobbyists, some collectors actually sell directly to the public! This means you can get fish shipped straight to your house without a middle man cost, and limited acclimation steps. Places like www.Sealifeinc.net even quarantine the fish and offer medicated treatments before selling a fish. This practice can be a life saver (literally) for your inhabitants.

The Tropical Western Atlantic may not have the diversity and great numbers of fishes found in other areas, but it certainly does have some strikingly beautiful fishes.

10 of the Most Beautiful Caribbean Fishes:

1. Harlequin Pipefish
2. Juvenile Porkfish
3. Redband Parrotfish
4. French Angel
5. Sunshine Chromis
6. Princess Parrotfish
7. Royal Gramma
8. Queen Angelfish
9. Juvenile Stegastes Damsels (longfin damsel, beaugregory damsel, dusky damsel)
10. Color Changing Wrasse (yellowhea wrasse, yellowcheak wrasse, clown wrasse)

Aquarium Setup

A Tropical Atlantic Biotope is set up the same way as any other reef aquarium. The basic principles of water flow, filtration, lighting, and aquascaping all apply. Common base rock is often used in reef tanks, and Eco-friendly cultured rock is also available from Atlantic suppliers. Fields of terrestrial rock have been places in the ocean and have been allowed to grow and inhabit fauna for several years. Companies like Sea Life Incorporated are licensed to grow this rock, harvest it, and use it to preserve surrounding coral reefs. Filter feeding corals that are photosynthetic are also easily purchased and make for stunning displays. If you prefer highly colored and textured corals the ricordea and zoanthids of the Atlantic can not be beat. And if you are into corals that grow fast and provide visual appeal with a gentle saw in the current, then the gorgonian are your choice. Add them together, and you have a rather interesting aquarium.

The challenges of setting up an Atlantic tank do not reside in the reefscape and husbandry. Instead, like most aquaria the challenge is in finding suitable tank mates and understanding their requirements. Selecting livestock choices prior to setting up the aquarium can save you a lot of troubles down the road. Here are some specifics on some common and not so common Atlantic inhabitants.

Common Atlantic Fishes

Butterflyfishes are beautiful, colorful, and abundant in the Caribbean. However, most of them are not reef safe, do not do well on prepared foods, and have a very poor survival rate in the hobby. These fish in general are best left for advanced hobbyists and those looking to study their captive care.

Angelfishes are beautiful, colorful and abundant in the Caribbean. Unlike many of the butterflyfishes these fish readily take prepared foods, often live for several years in captivity, and are all around great choices for the home aquarium. Some angels (especially the larger specimens) have been known to pick on tube worms, small polyps, and some corals. However, they are also easily trained to eat prepared foods and often do very well in reef aquariums.

Damselfishes of these waters are brilliantly colored, hardy, easy to feed, and serve as your typical damsel fish. Unfortunately this also means that many of them grow up to be bland, aggressive, and rather pugnacious. Great beginner fish for many hobbyists as well as some beautiful potential candidates for the nano reef aquarium.

Wrasses of the Caribbean are fantastic! These fish often do well in captivity, are frequently found in very large numbers, are often times very reef safe in captive settings, have wonderful color and personality, and are quite hard. Numerous of species are available that all make stunning additions as showpiece fish in the home aquarium.

Some fishes that are popular in aquariums are found and collected in the Caribbean waters. Hobbyists are often surprised to find out that these common aquarium fish are from the Atlantic.

10 Common Atlantic Fishes in the Aquarium Trade:

• Yellowheaded Jawfish
• Cleaner Goby
• Dwarf Seahorse
• Rock Beauty Angel
• French Angel
• Blue Tang
• Blue Chromis
• Chalk Bass
• Royal Gramma
• Queen Angelfish

Some fish would make great showpieces in home aquariums. They are incredibly interesting and can be perfect specimens for advancing the hobby and knowledge base. Aquarists looking to go beyond simply keeping fish, but really taking on an advanced topic may want to consider these fish.

10 of the Most Intriguing Atlantic Fishes:

1. Flying Gurnard
2. Scorpionfish
3. Trumpetfish
4. Filefish
5. Walking Batfish
6. Flounder
7. Harem of Wrasse
8. Grunts (group)
9. Glassy Sweeper (group)
10. Needlefish

 

Uncommon Atlantic Fishes

The Silverbody fishes is a general term used to describe a wide variety of fish families. These include the small fishes often found in schools, all the way up to large solitary fishes. Historically unpopular and virtually absent from the hobby the needlefishes, ballyhoos, jacks, mojarras and more are peaking the interest of advanced hobbyists. These fish all offer great potential for stunning displays, a chance to provide new information for the hobby, and unique aquatic systems. For hobbyist looking to stand out from the rest, these silverbody fishes are sure to do just that.

While not popular in the past, some of the Caribbean fishes are now making their way into the hobby. They are often overlooked, but with a growing trend in nano aquariums these fishes may be perfect for your captive care.

10 of the best Caribbean Fishes for the Nano Aquarium:

1. Grunts
2. Damsels
3. Reef Bass
4. Cardinalfish
5. Gobies
6. Blennies
7. Jawfish
8. Clingfish
9. Scorpionfish
10. Hawkfish

Ecofriendly Fish

These Lionfish are part of the ever growing population of lionfish that have colonized the Atlantic waters. These fish are not native to the Atlantic and their removal is an ongoing and never ending process. Collection and removal of these fish is completely Eco-Friendly and hobbyists who purchase them are doing their part to protect the Atlantic waters.

Atlantic Invertebrates

The Atlantic Ocean (tropical areas alone) offer a very large and wonderful selection of invertebrates. The sessile reef invertebrates like Gorgonia, Zoanthids, Anemones and more provide the reef habitat that makes the area so beautiful and full of life. Add to that wide array of mobile invertebrates such as cleaning shrimp, rock crabs, nudibranchs, urchins, sea stars, and sand worms, and you find yourself with a thriving ecosystem. All of these animals play an important role in the reef, and all of them are important in the home aquarium. Beginning hobbyists often overlook mobile invertebrates and focus on the big colorful fishes. However, with time hobbyists learn to appreciate the little forms of life that make an aquarium a living reef structure. These animals are fascinating and their interactions within a community create a complex reef habitat.

Some of the mobile invertebrates found in the Tropical Atlantic are colorful, unique, fascinating, and well suited for home aquaria. Each of these may make great additions to your aquarium and are worthy of further consideration.

1. Banded Shrimp
2. Ornate Snails
3. Ornamental Flatworms
4. Jellyfish
5. Reef Crabs
6. Anemone Shrimp
7. Mantis Shrimp
8. Horseshoe Crabs
9. Chitons
10. Sea Slugs

 

Conclusion

Often overlooked and underappreciated, the Atlantic biotopes are amazing aquariums. Sustainable inhabitants are here in our own backyards and ready for hobbyists to create new and interesting aquariums. Much can be learned about these animals from captive systems and hobbyists have a remarkable opportunity in front of them to participate in the process and progress.

While a great deal of interest has been shown in the characteristics of artificial daylight for reef aquaria, very little attention has been paid to the other natural illumination - moonlight. Although manufacturers have marketed moonlight simulators for a number of years, I've yet to see an in-depth discussion of the subject. This article will attempt to address that issue while discussing some misconceptions about lunar light. In addition, we'll define spectral characteristics of moonlight, light intensity, and length of natural lunar photoperiod, and ways to simulate moonlight. We'll also examine the effects (or non-effects) of moonlight on timing of coral spawning (and comment, albeit briefly, its effects on fish spawning behavior).

Lunar Photoperiod in Hawai'i

As we know, the lunar cycle consists of 29.5 days and is the basis for our calendar month. The lunar phase changes in a predictable manner and is due to relative positions of the moon, earth, and sun. Phase is not due to the earth's shadow falling upon the moon (this is referred to as a lunar eclipse). Figure 1 shows phases and approximate and approximate days of the lunar month.

Figure 2 shows the hours of potential moonlight in Hawaii. Data are based on times of sunrise/sunset and moonrise/moonset.

Moonlight Spectral Characteristics

Since moonlight is almost entirely reflected sunlight, one might reason that the moon's spectral signature is exactly that of sunlight - it is not. Data shown in Figures 3 & 4 reveal that moonlight is less blue and redder than sunlight (and this measurement was taken with a 'silvery' moon at its zenith. We often see a much more orange moon at moonset).

Moonlight Intensity

Moonlight intensity is determined by lunar phase and sky conditions. Figure 5 shows moonlight intensity (in lux) under ideal conditions. Figures 6 and 7 show full moon light intensities (PAR) as measured during two nights (just a few feet above sea level). Note that the intensities are lower than that reported by Jokiel (0.05 µmol·m²·sec, or about 1 lux). The low moonlight intensity reported here is due to a number of factors, including seawater aerosols in the air, thin high level clouds, and vog (a mixture of atmospheric moisture and volcanic smoke from the Pu'u O'o vent and Halema'uma'u caldera of the Kilauea volcano).

Factors Influencing Coral Reproduction - Order of Importance

Moonlight is but one factor influencing coral reproduction. If other factors (nutrition, physical parameters, etc.) are correct, these are believed to be important:

Temperature: Temperature seems to exert powerful control over coral reproduction. If the temperature is too high, coral health can suffer, while cool temperature may delay spawning until the next month's window (Hunter, 1988; Riddle personal observations). Temperature has been stated to be the influence of paramount importance in the reproductive cycles of marine invertebrates (Olive, 1995). In Hawaii, the temperature threshold is about 75F (24C; Dr. Paul Jokiel, personal communication).

Moonlight: Lunar cycles set the date of spawning in many coral species and the lunar calendar can be used to accurately predict it.

Daylight Photoperiod: Solar photoperiods influence coral reproductive efforts and set the hour and minute of spawning (Vize et al., 2008). The time of sunset is the fine-tuning factor for many marine invertebrates including at least some sponge and coral species.

Corals Don't Have Eyes - How Do They Sense Light? And What Do They See?

Gorbunov et al. (2002) found blue light at about 480nm (110nm width, half maximum) at very low light intensity caused a reaction among coral tentacles,although a description of photoreceptors involved was not part of the experiment.

In 2003, Levy et al. exposed corals (azooxanthellate Cladopsammia gracilis) the bubble coral Plerogyra sinuosa, the flower pot coral Goniopora lobata, Favia favus, and Stylophora pistillata) to various light wavelengths (400-700nm at 20nm intervals) and intensities (10µmol·m²·sec and 30 µmol·m²·sec; ~500 lux and 1,500 lux, respectively) and recorded tentacle contractions. Cladopsammia did not respond to any light treatment, while Plerogyra sinuosa and Favia favus contracted their tentacles when exposed to wavelengths between 400-520nm (violet-blue-green). Interestingly, Favia favus also responded to red light (660-700nm) at 30 µmol·m²·sec or ~1,500 lux (see light sensitivities of rhodopsin-like compounds and cryptochromes below).

Five years later, a rhodopsin*-like compound was found in the stony coral Acropora millepora (Anctil et al., 2007), explaining how corals sense light. Almost simultaneously, Levy et al. (2007) described cryptochrome** proteins sensitive to blue light in Acropora millepora. Other researchers have noted corals' responses to light suggesting rhodopsin-like compounds are found in at least some corals.

This ability to sense light explains how corals can grow towards light, and if overturned, can redirect their growth (this is call phototropism). It also explains how corals set their biological clocks through sensing daylight and moonlight.

*Rhodopsin is a photosensitive pigment found in many animals' eyes (including humans) within receptors called cones. Cones and their rhodopsin content enable us to see in very low light conditions. Rhodopsin collects light in wavelengths of about 400nm (violet) to red (at ~600nmn) but most strongly in the blue-green portion of the spectrum (Hunt, 1987).

**Cryptochromes (Greek for 'hidden color') are proteins sensitive to blue light and are found in photoreceptors of plants and animals.

Entrained Biological Rhythms versus Response to Environmental Factors

The act of coral spawning involves production of a number of compounds, and this may be the result of entrained rhythms or exposure to external stimuli. For our purposes, entrained rhythms are those that occur without external stimuli such as sunlight or moonlight. These are likely controlled genetically. Environmental factors (such as like or moonlight) can influence the production of compounds. Vize et al. (2008) found photoreceptors signal production of proteins important in annual spawning of the stony coral Montastrea cavernosa.

Fish Reproduction and Lunar Phase

Many fishes are known to spawn synchronously around a certain lunar phase and this timing may be species-specific. For instance, Takemura et al., 2004 discuss lunar phase and spawning of the golden rabbitfish (Siganus guttatus). These fish did not spawn when subjected to constant illumination, and those held in conditions of total darkness at night displayed altered spawning patterns. Pressley (1980) described the relationship of lunar phase and reproduction of the yellowtail damselfish, Microspathodon chrysurus.

It is an interesting notion that circadian rhythms play an important part in fish reproduction and that accurate simulation of lunar phase may be an important factor.

Light Spectra Transmission in Clear Seawater

As mentioned earlier, several researchers have found that some corals respond to blue light. It is perhaps not by coincidence that maximum penetration of light occurs at about 480-500nm. See Figure 8.

Moonlight and Coral Spawning

Moonlight is commonly believed to be one of the deciding environmental factors for timing of coral spawning. Jokiel (1985) examined numerous Pocillopora damicornis specimens and concluded planula release occurred around the time of the full moon. However, Hunter (1988) experimented with two Hawaiian Montipora species (M. verrucosa = capitata and M. dilatata) and found the following:

• Both sets of corals spawned simultaneously with control corals when exposed to constant simulated moonlight (at a flux of 0.01 µmol·m²·sec, or about 0.5 lux)
• When exposed to no simulated moonlight (constant new moon), 43% of the M. verrucosa spawned in sync with the controls, and in the next month, 1 week prior to the new moon. Montipora dilatata specimens also spawned in synch with controls in the first month, and then 8 days out of normal phase the next month.
• When maintained under simulated moonlight shifted 14 days out of phase, both coral species spawned simultaneously with controls, and then 2 to 12 days out of sync in the second month.

Artificial Moonlight

It is usually impractical to expose an aquarium to moonlight hence artificial means are preferred. In my 1995 book, The Captive Reef, I outlined a means of simulating moonlight with a blue incandescent lamp and a manual dimmer. Technology has come a long way since then and light-emitting diodes are now the preferred method. See Figure 9.

Figure 10 shows the typical spectral quality of a LED peaking in the blue portion of the spectrum at ~450nm.

Controllers

There are a number of controllers on the market claiming to simulate timing and variable intensity of natural moonlight. This article is not intended to review all those available. Instead, I describe the one I own - the Tunze Multicontroller 7095. This device's main function is that of controlling Tunze pumps but includes a LED for moonlight simulation. The only thing a hobbyist has to do is turn the moonlight LED on when the real moon is full and the controller automatically does the rest. A photo-sensor will turn the LED moon on when the aquarium lights go out and lunar phase intensity is controlled over a 29 day cycle. See Figure 11 for a close up view of the photo-sensor/LED and Figure 12 shows the spectral characteristics of the LED.

In Closing

Many corals contain photoreceptors (note their ability to almost always grow towards light). Some demonstrate responses to blue light, while at least one species can sense both blue and red light. Some show no response to light.

Moonlight is thought to play an important role in timing reproductive cycles of many coral and fish species. In corals, lunar cycles set the date of spawning, while the time of onset of darkness fine tunes the cycle and decide the hour and minute (then a release of hormones into the water induces mass spawning). An altered lunar phase may at least temporary disrupt spawning synchrony among at least some coral species. Lunar periodicity seems to play a role in timing of reproduction among at least some fish species. Interestingly, short term exposure of some fishes to constant artificial moonlight may have prevented spawning, while the same did not affect the patterns in some corals. It seems apparent that different taxa are affected differently by altered moon phases, if only temporarily.

Although moonlight appears white or silvery, use of LEDs producing blue light to simulate moonlight is, at least for some coral species, correct based to peer-reviewed evidence. Use of LEDs producing white light is likely to be OK as well, since these diodes are essentially blue LEDs doped with phosphors that fluoresce longer wavelengths. However, the light intensity of the light produced by even a single blue LED has the potential to be brighter than natural moonlight measured here in Hawaii. Light penetration in aquaria, with their usually shallow (and hopefully clear!) waters, should not be an issue, so using LEDs with a maximum wavelength of 450 or 460nm may actually be an advantage due to their lower output at 480nm.

Since most PAR meters' minimum respond is '1', these units are useless in determining proper placement of a light source in order to mimic natural moonlight intensity. On the other hand, a lux meter can measure moonlight at its maximum intensity although the reading will be ~1. Hence, placement of the LED for providing proper intensity will likely have to be estimated visually. At present, the effects of over-illumination of a reef aquarium at night are unknown but it is possible that it might affect fish or invertebrate spawning behavior.

A number of controllers with abilities to simulate lunar phase are on the market. In absence of one, a handy hobbyist can make a manually-controller lunar simulator with a low wattage incandescent lamp and a rheostat.

Testing Equipment

Spectral characteristics of the moon and LED were measured with an Ocean Optics USB2000 spectrometer and SpectraSuite software. Data were downloaded to an Excel worksheet for post-processing. Moon intensities were recorded by a Li-Cor 1400 quantum meter/datalogger and cosine-corrected quantum sensor.

Acknowledgement

Thanks to my brother David for supplying the photograph of the moon.

Questions? Comments? Please post below or contact me at RiddleLabs@aol.com.

References

1. Anctil, M., D. Hayward, D. Miller, and E. Ball, 2007. Sequence and expression of four coral G protein-coupled receptors distinct from all classifiable members of the rhodopsin family. Gene, 392(12): 14-21.
2. Brady, A., K. Snyder and P. Vize, 2011. Circadian cycles of gene expression in the coral, Acropora millepora. PLoSOne Online.
3. Gorbunov, M., Z. Kolber, M. Lesser, and P. Falkowski, 2002. Photoreceptors in the cnidarian hosts allow symbiotic corals to sense blue moonlight. Limnol. Oceanogr., 47(1), 2002, 309-315.
4. Hunt, R., 1987. Measuring Colour. Fountain Press, Kingston-upon-Thames, England. 344 pp.
5. Hunter, C., 1988. Environmental cues controlling spawning in two Hawaiian corals Montipora verrucosa and M. dilatata. Proc. 6^th Int. Coral Reef Symp., Australia. 2:727-732.
6. Jerlov, N., 1976. Marine Optics. Elsevier Oceanography Series, Elsevier Sci. Publ. Co., New York. 231 pp.
7. Jokiel, P., 1985. Lunar periodicity of planula release in the reef coral Pocillopora damicornis in relation to various environmental factors. Proc. 5^th Int. Coral Reef Congress, Tahiti. 4: 307-312.
8. Levy, O., L. Appelbaum, W. Leggat, Y. Gothlif, D. Hayward, D. Miller, O. Hoegh-Guldberg, 2007. Light-responsive cryptochromes from a simple multicellular animal, the coral Acropora millepora. Science, 318 (5849):467-470.
9. Levy, O., Z. Dubinsky, and Y. Achituv, 2003. Photobehavior of stony corals: Responses to light spectra and intensity. J. Exp. Biol., 206: 4041-4049.
10. Olive, P., 1995. Annual breeding cycles in marine invertebrates and environmental temperature: Probing the proximate and ultimate causes of reproductive synchrony. J. Therm. Biol., 20(1, 2): 79-90.
11. Pressley, P., 1980. Lunar periodicity of the yellowtail damselfish, Microspathodon chrysurus. Environ. Biol. Fishes, 5:155-159.
12. akemura, A., E. Susilo, M. Rahman and M. Morita, 2004. Perception and possible utilization of moonlight intensity for reproductive activities in a lunar-synchronized spawner, the golden rabbitfish. J. Exp. Zoology, Part A: Comp. Exp. Biol., 301A, 10: 844-851.
13. Vize, P., J. Hilton, A. Brady and S. Davies, 2008. Light sensing and the coordination of coral broadcast spawning behavior. Proc. 11^th Int. Coral Reef Symp., Ft. Lauderdale, Florida.

There may be scores of distinct biogeographic regions that have yet to be adequately represented in public aquaria, much less in the aquarium trade. A great many of them lay claim to a multitude of interesting, beautiful and diverse species. The islands of New Zealand serve as a particularly good example of this.

The waters surrounding this island nation are inhabited by as many as 650 fish species. Despite the country's remoteness, a surprisingly small number of its fish fauna is endemic; it really is an inter-oceanic crossroads of sorts, falling within the range of drift between East Australia, South Africa, and Japan. Hence, while it claims relatively few unique fish species, New Zealand is truly unique in that there one can find so many disparate varieties of fish occurring together.

Its environs lie within a latitudinal belt that stretches from the more or less tropical Kermadec Island in the north to sub-antarctic Macquarie Island in the south. The majority of fishes of potential interest to the home aquarist, however, can be found in its subtropical and temperate inshore rocky reef habitats. These rich biological communities may be further subdivided into a number of distinct habitats, from shallow tidepools to lush kelp forests. This particular brand of rocky reef not only occurs in New Zealand proper, but actually abounds within a longitudinal belt that runs from New South Wales to Lord Howe Island to the Poor Knights Islands.

Whether because, or despite, the county's proximity to so many extraordinary marine habitats, interest in marine aquarium keeping appears to be weak there. One resident saltwater fish importer complains, with at least some incredulity, that out of a population of 4 million, probably no more than a 1,000 individuals keep marine aquaria. This is perhaps attributable at least in part to the New Zealand government's strictly imposed quarantine period for imported aquarium fish (3 weeks for saltwater livestock, 6 weeks for freshwater livestock), which raises retail prices considerably. Some ornamental fish and invertebrate species are prohibited altogether. As koi are no longer allowed within its borders, New Zealand's pond keepers have increasingly been experimenting with native freshwater fish species (local retailers have even begun to offer certain native species for this market). Likewise, a handful of marine aquarists there have made attempts (some quite successfully) to create attractive aquarium exhibits with locally obtained flora and fauna.

These successes pose an interesting question: Could any of the species from this region ever become popular in the global ornamental fish trade? One might suppose so, given hobbyists' apparently increasing appetite for rare and unusual fishes. Subtropical and temperate aquaria in particular have steadily gained prominence, with ever more offerings of such species to be found on LiveAquaria.com and now even specialty suppliers such as Coldwater Marine Aquatics.

A growing awareness of the fishes from these areas could lead to a stronger demand in the trade, which could in turn spur suppliers worldwide to distribute them. Harvest and export from New Zealand would undoubtedly serve to fill voids already existing from closures enforced in nearby areas (e.g., the Lord Howe Island group).

The following overview is presented with the aim of contributing to such an awareness, if not a greater representation of these remarkable species in the aquarium fish trade. This multimedia work is comprised mainly of still images by photographer, diver and adventurer Ian Skipworth, video by marine aquarium hobbyist and videographer "corralimorph" (otherwise known at Aquaria Central as "coldmarine007"), and illustrations by biologist, author and artist Tony Ayling. Material in the captions borrows heavily from Collins Guide to the Sea Fishes of New Zealand by Tony Ayling and Geoffrey J. Cox.

Note: Fortunately for New Zealand aquarium hobbyists, there is no permit required for harvesting/keeping marine species provided they meet the size and bag limit requirements and are taken by legal means. Unfortunately for the rest of the world, these fish presently cannot be kept for sale (including barter or trade), breeding or distribution (reseeding, etc.). Would-be exporters and other stakeholders could work with New Zealand's Ministry of Fisheries, however, to relax certain restrictions (particularly those meant to protect sportfish/foodfish stocks) to allow for a well managed marine ornamental fishery. Such industries would not only create economic opportunity for a great many of its citizens, but would furthermore promote a global awareness and appreciation of its rich coastal resources.

For additional regulatory information, please view the following link: http://www.fish.govt.nz/en-nz/Recreational/default.htm

References

1. Ayling, Tony and Geoffry J. Cox. 1984. Collins Guide to the Sea Fishes of New Zealand. William Collins Publishers Ltd.
2. http://www.fishbase.org
3. http://www.ianskipworth.com/index.shtml
4. http://www.aquariacentral.com/forums/showthread.php?150891-Check-out-this-cold-marine-reef-tank

At present, the selection of tank bred marine aquarium fishes is modest, but growing. Accordingly, more and more conscientious hobbyists are choosing cultured over wild caught animals. A handful of particularly good (though frequently overlooked) tank bred candidates for the home aquarium belong to the genus Meiacanthus, the fang blennies.

The fang blennies (or poison-fang blennies, or sabre-tooth blennies) include a considerable number of highly specialized combtooth blenny species from several genera. While many of these are known to parasitize or prey on other fish, Meiacanthus feeds primarily (though not at all exclusively) on plankton.

Meiacanthus spp. occurs widely across the Western Pacific and Indian oceans. These fishes generally inhabit shallow water environments, though some (such as recently described Meiacanthus erdmanni) have been found at depths as great as 70 meters. They are (with the exception of Meiacanthus anema) strictly marine.

Meiacanthus spp. adapts well to captivity. These surprisingly tough fishes are tolerant of suboptimal water conditions and are resistant to disease. They readily accept a wide variety of foods. They are usually peaceful toward their own kind and others. They reach relatively small adult sizes, and so are appropriate for smaller aquaria.

There is a wide variety of hue and pattern within the genus. The distinctive coloration, accentuated by their sleek body shape, makes for an exceptionally attractive animal.

Blennies are widely appreciated for their abundance of charm; fang blennies are no exception here. They are rather busy and inquisitive, and appear to be very aware of their surroundings. Unlike many of their blenny brethren, they have functional swim bladders and spend much time moving about in open water. While they can be somewhat cryptic, they are generally far less secretive and skittish than other blenniids. Probably, much of their apparent self-assurance is derived from their possession of an especially potent defensive apparatus.

The two enlarged, grooved canine teeth for which fang blennies get their name are situated in the lower jaw. Unlike other fang blenny genera, Meiacanthus usually employs its weaponry only to defend itself or its territory. When seriously threatened, it will open its jaws wide to bear its teeth. Each "fang" is equipped with venomous buccal glands. Venom is delivered with pressure to the glands. While not especially dangerous to most people, fang blenny bites can be quite painful. Fortunately, because of its small mouth, envenomation of humans by this animal is unlikely. That being said, one should never attempt to hand capture or hand feed a fang blenny.

Some fang blennies can be successfully kept in tanks as small as 10 gallons, but will be most comfortable when housed in enclosures of 20-30 gallons or more. They do not require any special care. They will, however, appreciate an abundance of rocky caves and crevasses. They can be quite jumpy, so a tight-fitting lid is highly recommended.

Fang blennies are not particularly difficult (at least as far as marine fish go) to breed and rear in captivity; indeed, most advanced hobbyists have the requisite skills to raise them. They are, however, difficult for most to sex. It is usually best to introduce multiple individuals to the broodstock tank and allow them to form harems. Subordinate males should be removed to spare them from harassment. A single male might court a number of females, and even tend to eggs from several females in a single nest. A full nest is comprised of about 100 adhesive 1mm eggs. A 3-5 inch section of 1-inch PVC pipe serves as a very convenient nest site for both fish and fishkeeper. There are many variations on techniques for nest collection/incubation; typically, the pipe is transferred (about a day prior to hatching) to a hatching tank/tub, fixed to a standpipe, and aerated gently from below with an air stone. While the incubation time varies somewhat depending upon species and temperature, Meiacanthus spp. eggs usually hatch around day 8. Larvae are small (approximately 3 mm in length) and thusly require small live first foods (e.g., rotifers).

To date, at least 28 Meiacanthus species have been described:

1. Meiacanthus abditus Smith-Vaniz, 1987

2. Meiacanthus abruptus Smith-Vaniz & Allen, 2011

3. Meiacanthus anema Bleeker, 1852 (threadless blenny)

4. Meiacanthus atrodorsalis Günther, 1877 (forktail blenny)

5. Meiacanthus bundoon Smith-Vaniz, 1976 (bundoon blenny)

6. Meiacanthus crinitus Smith-Vaniz, 1987

7. Meiacanthus cyanopterus Smith-Vaniz & Allen, 2011

8. Meiacanthus ditrema Smith-Vaniz, 1976 (one-striped blenny)

9. Meiacanthus erdmanni Smith-Vaniz & Allen, 2011

10. Meiacanthus fraseri Smith-Vaniz, 1976

11. Meiacanthus geminatus Smith-Vaniz, 1976

12. Meiacanthus grammistes Valenciennes, 1836 (striped blenny)

13. Meiacanthus kamoharai Tomiyama, 1956

14. Meiacanthus limbatus Smith-Vaniz, 1987

15. Meiacanthus lineatus De Vis, 1884 (lined blenny)

16. Meiacanthus luteus Smith-Vaniz, 1987 (yellow blenny)

17. Meiacanthus mossambicus Smith, 1959 (Mozambique blenny)

18. Meiacanthus naevius Smith-Vaniz, 1987

19. Meiacanthus nigrolineatus Smith-Vaniz, 1969 (blackline blenny)

20. Meiacanthus oualanensis Günther, 1880

21. Meiacanthus phaeus Smith-Vaniz, 1976

22. Meiacanthus procne Smith-Vaniz, 1976

23. Meiacanthus reticulatus Smith-Vaniz, 1976

24. Meiacanthus smithi Klausewitz, 1962 (disco blenny)

25. Meiacanthus tongaensis Smith-Vaniz, 1987

26. Meiacanthus urostigma Smith-Vaniz, Satapoomin & Allen, 2001

27. Meiacanthus vicinus Smith-Vaniz, 1987

28. Meiacanthus vittatus Smith-Vaniz, 1976 (one-striped blenny)

Only a fraction of these are regularly encountered (much less cultured) in the trade; this will almost surely change with continuing imports of these species.

Conclusion

As ornamental fish, fang blennies of the genus Meiacanthus have it all--sturdiness with elegant good looks, individual character with great adaptability, peacefulness with the ability to stand up to aggressors. Owing to their diminutive size, they are appropriate for many smaller aquaria. The relative ease with which they can be cultured might make them especially attractive to breeders. Captive bred specimens of common fang blennies (e.g., Meiacanthus oualanensis) are now widely available; the availability of captive bred specimens of less common fang blennies (e.g., Meiacanthus tongaensis) will likely increase in the near future; it is entirely plausible that even presently unavailable species (e.g., Meiacanthus geminatus) will be produced on a commercial scale in years ahead. Come what may, these fishes undoubtedly will hold the interest of marine aquarium hobbyists for a very long time.

References

1. www.fishbase.org.
2. http://www.practicalfishkeeping.co.uk/content.php?sid=4282
3. Losey, GS. 1972. Predation protection in the poison-fang blenny, Meiacanthus atrodorsalis, and its mimics, Ecsenius bicolor and Runula laudandus (Blenniidae). Pac Sci 26(2): 129-139.
4. Smith-Vaniz, William F. and Gerald R. Allen. 2011. Three new species of the fangblenny genus Meiacanthus from Indonesia, with color photographs and comments on other species (Teleostei: Blenniidae: Nemophini). Zootaxa 3046: 39-58.
5. Fishelson, Lev. 1976. Spawning and larval development of the blenniid fish Meiacanthus nigrolineatus from the Red Sea. Copeia 1976: 798-800.
6. Wittenrich, Matthew L. 2007. The Complete Illustrated Breeder's Guide To Marine Aquarium Fishes. T.F.H. Publications, Inc.

Subfamily Amphiprioninae, the clownfishes, is a diverse group. It is divided into six species complexes, including the Clarkii Complex, the Skunk Complex, the Tomato Complex, the Saddleback Complex, the Percula Complex, and the maroons. In terms of number of member species, the latter two are the smallest; indeed, with only two and one member each respectively, neither is (strictly speaking) really even a complex.

The Percula Complex (Amphiprion ocellaris and Amphiprion percula) and the maroons (Premnas biaculeatus) are together the subject of this discussion; the other four complexes have each received attention here in earlier parts of this series. The two are presented here together on account of their superficial similarities, as well as their apparently very similar lineages.

These three species have for long been among the best-represented members of the subfamily within the ornamental fish trade. Their likenesses--particularly that of Amphiprion ocellaris--frequently serve as icons for anything and everything marine, and are recognized even by those who have never owned an aquarium. They have lured countless individuals into the hobby, and continue to command the interest of even the most advanced aquarists. Perhaps most importantly, they stand out as being among the first marine aquarium fishes to be successfully reared in captivity. It is truly difficult to overstate how important these distinctive fishes have been, and are, to the ornamental fish trade.

Premnas biaculeatus, Amphiprion ocellaris, and Amphiprion percula will likely retain a high demand in the trade as new color morphs continue to be developed; considerable work has already been done in the selective breeding of the latter two species. Some aquarists prize these novel varieties (which often bear exaggerated desirable traits) and are increasingly willing to pay premium prices for well-bred specimens. Then again, other aquarists prefer only "wild-type" specimens and view most aberrant color forms as unnatural, if not flawed. In point of fact, many of the traits we see in "designer" varieties can be observed, at least to some degree, within wild populations.

Certain differences between the two complexes are noteworthy. Species in the Percula Complex are among the physically smallest members of the subfamily, while the maroons are among the largest; moreover, the former is relatively peaceful while the latter is notorious for its pugnacity. Still, similarities between the two--most notably with respect to body shape and swimming habit--are striking.

Many fish biologists and many fish enthusiasts alike have held that the maroons are closely related to the Percula Complex species. Recent work using molecular phylogenetic analysis supports this position, even while calling longstanding notions about the nature of this relation into question. Results from these investigations suggest that these three species are very similar to the ancestral clownfishes. This is particularly surprising in that they certainly appear to be more derived than, say, members of the Tomato Complex, which bear a greater morphological resemblance to their damselfish cousins and are more generalistic in their associations with host anemone species. Being as results from these studies indicate that Amphiprion ocellaris and Amphiprion percula are more closely related to the maroons than they are to the rest of the subfamily, it really may be more appropriate to assign them to the genus Premnas. Here, however, they will be presented in line with conventional taxonomy.

The Percula Complex in profile

Common (or false percula) clownfish (Amphiprion ocellaris, Cuvier, 1830)

The common clownfish occurs in calm, shallow, reef-associated waters throughout the Indo-West Pacific Ocean from Southeast Asia to northwestern Australia (tropical). It is typically associated with the sea anemone species Heteractis magnifica, Stichodactyla gigantea, and Stichodactyla mertensii. One designation for the so-called common clownfish, false percula clownfish, serves as a great example of how unnecessarily confusing common names can be. Though it is a fairly hardy aquarium fish, it has earned a reputation as a poor shipper. It is distinguished by (usually) having thin, black edging around its bands and by possessing 10-11 spines in the first dorsal fin.It reaches a maximum length of 11 cm.

Orange (or true percula) clownfish (Amphiprion percula, Lacepède, 1802)

The orange clownfish occurs in lagoons and seaward coral reefs in the Western Pacific Ocean from the Great Barrier Reef to the Solomon Islands (tropical). It is typically associated with the sea anemone species Heteractis crispa, Heteractis magnifica, and Stichodactyla gigantea. Though it generally adapts well to captivity, it can be intolerant of suboptimal water conditions. It is distinguished by (usually) having thick, black edging around its bands and by possessing 9-10 spines in the first dorsal fin. It reaches a maximum length of 11 cm.

The maroons in profile

Maroon (or spine-cheeked) clownfish (Premnas biaculeatus, Bloch, 1790)

The maroon clownfish occurs in lagoons and protected coastal waters throughout the Indo-West Pacific region (tropical). While the white-stripe strain is widely distributed, the gold-stripe strain appears to be restricted to Sumatra. It is typically associated with the sea anemone species Entacmaea quadricolor. It is distinguished by its maroon to mahogany red adult coloration and its set of prominent preopercular spines. It can be vicious towards other clownfish, and should therefore be kept singly, if not in established pairs; pairings are best made by introducing a very large individual to a tank housing a much smaller individual. Females grow considerably larger than males. The maroon clownfish can reach lengths of over 17 cm.

Conclusion

It pretty much goes without saying that the common, orange, and maroon clownfish are well known and well represented in the marine aquarium hobby. Tank-bred specimens are now widely available in trade; most agree that these are far easier to keep than their wild counterparts. Especially in the case of the common and orange clownfish, a wide variety of color forms are yet being developed. Ones preference for one of these forms, or of strictly wild-type forms, is really only a matter of personal predilection. Certainly, newer (and bolder) varieties are forthcoming. With the commercial hatchery production of these fishes now well underway, it is perhaps only a matter of time until maroons come in "fantail," "pearlscale," and "bubble-eye." That notwithstanding, the typical forms we have always admired are no more likely than red roses to lose their strong popular appeal.

References

1. Wilkerson, Joyce D. Clownfishes: A Guide to Their Captive Care, Breeding, & Natural History. Shelburne, VT: Microcosm Ltd., 1998.
2. Fautin, Daphne G. and Gerald Allen. Anemonefishes and Their Host Sea Anemones. Morris Plains, NJ: Tetra Press, 1994.
3. Skomal, Gregory B. Clownfishes in the Aquarium. Neptune City, NJ: T.F.H. Publications, Inc., 2004.
4. Elliott, J. K., S. C. Lougheed, B. Bateman, L. K. McPhee and P. T. Boag. "Molecular Phylogenetic Evidence for the Evolution of Specialization in Anemonefishes." Proceedings: Biological Sciences Vol. 266, No. 1420 (Apr. 7, 1999), pp. 677-685.
5. http://fishbase.org
6. http://www.sustainableaquatics.com

First, a little history... There had been a lot of activity, experimentation, and commentary in the late 60s and early 70s on the possibility of rearing marine tropical fish in numbers but no one had yet succeeded. I was lucky; I was in the right place at the right time with the right experience. I had worked from 1969 to 1971 developing the technology for controlled spawning and larvae culture of the Florida pompano, and from that I knew what marine fish larvae needed in order to survive. I also picked the right fish with which to begin the work. If I had picked, Oh, pigmy angelfish, for example, I might be still working at it. I explained in the article why I chose the "Percula" clownfish for the first experiments.

At that point, the hobby did not really distinguish between A. percula, the orange and/or percula clownfish, and A. ocellaris, the common and/or false clownfish. In fact, few hobbyists were familiar with taxonomic conventions and the use of scientific names was only something that those fancy pants scientist types used once in a while. In the hobby, the only clownfish that was typically available was the common clownfish, A. ocellaris. But in the popular literature the percula clownfish was most commonly illustrated, and so the common clownfish that filled the tanks of this fledgling hobby was almost universally given the erroneous common name "Percula clown". The two species are very close in morphology; there are some subtle color differences and typically 10 dorsal spines in A. percula and 11 dorsal spines in A. ocellaris. A. percula was described in 1802 by Lacepede, and A. ocellaris in 1830 by Cuvier. Given that A. percula was the first described, that name was most used in the early literature, and thus picked up by the early marine aquarists. Books by Gerald Allen and Daphne Fautin eventually ended the lay confusion (almost) between these species. Now, of course, we also have to contend with numerous "breeds" and hybrids of these same species. It is an exciting time for clownfish breeders.

At that time there were relatively few species of marine tropical fish available to hobbyists. Clownfish were among the most popular marine fish, but also quite difficult because most were collected with cyanide. They were also subject to external parasites, and shipment and early captivity mortality was very high. But even with my experience with pompano, it was a culture project with very little extant information to guide the effort; and with limited resources, a lot of experimentation and intuitive guessing on how to resolve problems was required. The thing that always helped me with development of culture procedures with new species was to learn as much as I could about the natural history of the species under culture, the environment, the diet, the reproductive modes, etc., and use that knowledge as a base for development of adequate substitutes for that organism's basic requirements for survival.

As with the early development of any new technology that holds a promise of commercial value, the early days of marine fish culture were shrouded in secrecy, or least that attempt was made. Thus my article was long on biology and short on technology. It was important, however, to provide enough detail in text and photos to establish with certainty that repetitive culture of relatively large numbers of juveniles had been accomplished. Within a few years, of course, the basic culture techniques, and many improvements as well, soon became relatively well known. Over the years, subsequent articles, books, and websites have provided great detail on the original and many additional techniques. The Marine Aquarium Handbook (now in the 3^rd edition) and my book on rearing the orchid dottyback, many very significant recent articles and scientific papers, and books by Hoff, Wilkerson, and Wittenritch have now greatly expanded knowledge and "how to" information on marine ornamental fish culture. And now the information for large and small scale culture of many species (but not enough) of marine fish is readily available. My original article is of historical interest, but still provides good information on the biology of clownfish culture.

Salt Water Aquarium, The international magazine for marine aquarists

Introductory comments from Robert P. L. Straughan, editor, Salt Water Aquarium magazine

March-April, 1973, Volume 9, Number 2

TANK RAISED CLOWNFISH!
SPECIAL SPAWNING ISSUE
A MILESTONE IN THE HOBBY
BREEDING THE CLOWNFISH, Amphiprion ocellaris
By MARTIN A. MOE, JR., MARINE BIOLOGIST

Breeding marine fish has often been termed impossible, improbable, difficult and prohibitively expensive. It is actually none of these, as this article will show; however, it is time consuming and does require a good deal of specialized knowledge. This is not a "how to" article or a scientific paper since the techniques of rearing are still under development and many problems are yet to be solved, but I hope that it will stimulate increased interest in the hobby of maintaining marine fish and show that the prospect of rearing some of the marine tropical fish in large numbers may not be far off.

Fishes of the genus Amphiprion, particularly the common clownfish A. ocellaris (percula) are among the most popular of marine aquarium fish. Their hardiness, vivid coloration, engaging personality and relative abundance are good reasons for their popularity. These traits alone are cause enough to investigate the possibilities of controlled reproduction and a study of what is known of their life history confirms their candidacy for breeding experimentation. Clownfish are demersal spawners, attaching their eggs to hard surfaces near the base of an anemone. They guard and aerate the eggs from spawning to hatching, a period of 7 to 9 days, after the fashion of cichlids. The larvae are large at hatching, about 4 mm in length, have eyes and mouth parts fully formed, and are ready to begin feeding within the first 24 hours of hatching. The adults mature at small size, 50 to 100 mm, and have a limited range, usually the immediate vicinity of an anemone. These biological characteristics make it relatively easy to provide the necessary environment to stimulate natural spawning.

Dr. Gerald R. Allen (1) has compiled a recent and thorough review of the taxonomy and biology of the genus Amphiprion and he reports in this work of rearing 3 A. chrysopterus and one A. tricinctus through the larval stages on dried particulate food, This and other accounts of rearings of Amphiprion (2) (3) and (4) reported in the literature, made A. ocellaris an obvious choice for the first rearing attempts. The following work was conducted partly as an extension of a hobby and partly as independent research on reproduction in marine fishes while attending the University of South Florida.

Spawning

The project began in July, 1972, with the construction of two 55 gallon tanks destined to serve as spawning aquaria. Costs were cut markedly through constructing all parts of the tanks and filters with inexpensive, readily available materials. (Perhaps the details of construction will form a later article.) One of these tanks was established with natural sea water and small local fish were used to provide the nitrogenous waste to activate the filter bed. The other was filled with artificial sea water and the filter bed was activated chemically with ammonium chloride. The latter method resulted in a more trouble free tank than the former. Each tank was provided with full spectrum lighting and an attractive decor of construction stone. The photoperiod and temperature were adjusted to provide maximum stimulation of the fish's endocrine system and then the trauma of establishing the filters began. The tanks were ready for occupation about mid-September. Four A. ocellaris that seemed to be already mated and two large anemones of the genus Stoichactis were purchased at Scott's Highway Aquarium in St. Petersburg and the experiment began. A diet specially compounded of shrimp, clams, chicken gizzards and certain marine algae and vitamins was fed twice a day. The fish took immediately to the anemones and their general behavior was soon much like that described in the literature for the genus Amphiprion in the wild. The fish spent most of their time bathing in the anemone and hovering just above it protecting their anemone from all real and apparently many imaginary intruders. Movements many feet away from the aquaria would send them charging against the glass or scurrying in rapid retreat into the protective custody of the anemone.

Only one pair engaged in spawning activity. This was the pair that occupied the tank established with artificial salt water, although by this time the initial water had been diluted with natural sea water to reduce the nitrate accumulation. The pair in the tank established with natural sea water and local fish had problems with external parasites and had to be treated several times. Also, as they gained in size the suspicion that they were both females became more of a certainty. They are almost equal in size and both have the roundness of the abdomen that seems characteristic of females.

The spawning pair are unequal in size and vary in general shape. The female is the largest of the pair, approximately 80 millimeters long and has a well-rounded abdomen. The male is about 60 millimeters long and has a narrow abdomen and a much smaller appetite than the female. The first spawning occurred on November 3, 1972. There was some indication of impending spawning in the fullness of the female and for a few days before spawning each fish would occasionally bite gently at the abdomen and vent of the other. Spawning occurred, as it did in all subsequent 5 spawns, in the afternoon hours. About one hour before spawning, the pair actively cleans the rock that will receive the eggs by biting the substrate and aggressively jerking the head from side to side. The afternoon spawning could be accurately predicted in the early morning by the extended ovipositor of the female. The ovipositor, a blunt, rather large pinkish organ, did not retract until several hours after spawning. The male's genital papilla was small, white in color, sharply pointed and appeared only shortly before, during and shortly after spawning. Rapid chasing before spawning or rapid vertical movements as reported by other authors did not occur.

Toward the .end of the surface cleaning activity, the female began to make frequent passes over the rock with the tip of her ovipositor dragging over the cleaned surface. These passes became more frequent until after about 15 minutes the first eggs appeared. These were a bright orange-yellow, about 1 mm in diameter and 2 mm in length. They passed from the ovipositor and immediately adhered by one end to the rock. The female swam in a circular course around and through the cleaned area depositing the eggs as she passed. After every few passes the male swam over the enlarging patch of eggs and fertilized them. No milt (sperm) could be observed in the water, but even eggs placed one or two inches from the main patch were fertilized. During this activity both fish nipped at the anemone and caused it to retract from the area where the eggs were deposited. The nest was always made in an area covered by the anemone.

The eggs adhered to the rock by means of a short pedestal composed of innumerable small fibers that fanned out over the rock. The yolk contained an oil droplet that may aid the buoyancy of the eggs but did not give them positive buoyancy since they sink if detached from the rock. Each egg could move almost 180 degrees in any direction with water movement, thus the patch of eggs was in constant motion under the careful fanning of the male. The male was clearly in charge of the eggs. He rarely left them for more than a few seconds during the entire period of incubation. The female would give them an occasional mouthing or a quick tail sweep, but did not guard them constantly even though she rarely left the vicinity of the anemone. The male usually positioned himself on topof the eggs and kept them moving with frequent sweeps of his pectoral and caudal fins. He would frequently "mouth" the eggs also, which consisted of positioning himself vertically over the eggs and while maintaining this orientation with quick movements of his fins, he gently bit at them in much the same way as the rock was initially cleaned for spawning. The female also engaged in mouthing the eggs but at more infrequent intervals than the male. This activity continued until the eggs hatched. Although other authors report increased fanning activity the day before the eggs hatch, I did not notice an increase in nest care activities at that time. However, during hatching, which always occurred at night at least several hours after the onset of darkness, the male was constantly active at the nest. This pair spawned 6 times in about 2 months, Nov. 3, Nov. 14, Nov. 30, Dec. 11, Dec. 24, and Jan. 6 were the dates of spawning. Behavior was similar during all spawns and number of eggs spawned varied from an estimated 500 to 800.

Hatching and Larval Recovery

The problem that caused the greatest limiting factor to the number of fish that were reared was not larval mortality, but recovery of the larvae after hatching. This is primarily a manipulative problem and can be solved through experience. Reports in the literature stated that hatching for most Amphiprion takes place on the night of the seventh day after hatching, and sure enough the eggs from the first batch of eggs looked ready to hatch on the seventh day. The reflective pigment of the eyes was well developed, the mouth parts were formed and the embryo was twitching within the chorion (egg shell) of the egg. Recovery of the larvae after hatching in the breeding aquarium was sure to be a struggle and not a positive method of recovery, so that about 75% of the eggs were carefully removed from the rock without disturbing the anemone and with minimal disturbance to the adults. The male resumed care of the remaining eggs when the operation was complete. These eggs, destined to hatch in a few hours (1 thought) were carefully incubated in the prepared larval tanks and I waited anxiously for hatching. It has been said that it's not nice to fool Mother Nature and I was ready to believe it. The eggs did not hatch in the incubating dish or on the rock. Although egg incubation in the hanging dishes was feasible for a few hours, it was not successful for a period of 30 to 48 hours. The eggs did not hatch until the night of the ninth day and by that time I had taken most of the remaining eggs trying to figure out what was happening and had almost given up on them hatching. As a result only 9 larvae were recovered on the day of hatching. Eight of these were reared to the juvenile stage.

The second spawn did not go much better. I waited until the ninth day to take the eggs, and did not take as many off the rock this time. However, a temperature drop in the aquarium of about 3 degrees C caused a delay in development and hatching for several days and the larvae did not appear until the night of the eleventh day after spawning. I also learned that an unattached egg has greater difficulty hatching than an attached one. As superbly illustrated in Dr. Allan's book on page 249, Amphiprion eggs hatch tail first. There is a tendency for a larvae hatching from an unattached egg to retain the egg capsule over the anterior portion of the body and swim about pushing the capsule before it. When this happens the larva soon succumbs to oxygen deprivation. Although it was possible to give the hatching larva an assist with a couple of pins, it was not a practical method of getting good larvae for rearing. An estimated 50 larvae were recovered from this spawn and 43 made it through the larval stage. The majority of these were recovered from the breeding aquarium after hatching by locating and concentrating the larvae with a flashlight and siphoning them from the tank. Undoubtedly some were injured by this treatment, but at least 90% were recovered without injury.

The third spawn hatched in 8 days and recovery was entirely accomplished by siphoning the larvae from the breeding tank after hatching. Many larvae were recovered but still only an estimated one fifth of the entire spawn was captured. Immediately after hatching the larvae swim rapidly and apparently without direction for several minutes, and if during this period they encounter the gravel bottom of the tank or the inside of a shell or other restricted area, they probably never survive to the free swimming stage. The total number taken from the aquarium from this spawn was estimated at 125, and a total of 115 were taken from the larval tank in the post larval stage. Thus recovery after hatching was improving and survival rates remained high. Great things were expected from the next spawns for most of the problems had been identified, if not solved, and confidence was high.

Mother Nature struck again. The fourth, fifth and perhaps the sixth spawns were complete wipe outs. All went well until the fifth day after spawning. At this time I noticed a whitening of the eggs and close examination revealed a granular whiteness of the yolk. The embryo appeared normal, but stunted, and hatching never occurred. When the same thing happened on the fifth spawn, I took some of the infected eggs to a friend At the Florida Department of Natural Resources Marine Research Laboratory to take a look at them through the microscope and see if we could determine the causative agent. We did find some "bugs" in the eggs in large numbers and made a very tentative identification putting them in the microsporida. If such is the case, the infection is probably located in the ovary of the female and may have been introduced with some food item, although it is possible that it entered with the natural sea water or was already in the fish in another developmental stage before she spawned the first time. This type of infection does yield to the SSA treatment (Sterilize and Start Again) so future experimentation must wait until new set ups are prepared. This problem can be avoided, unless it is inherent in all female Amphiprion through careful processing of water and food to prevent introduction.

Larval Rearing

Good success was obtained in rearing the larvae from the above reported spawns. Survival to the post larval stage was estimated in the second and third spawns, but could not have been less than 60% and was probably closer to 80%. The post larval stage was entered when the fish became 1/4 inch long, had developed the orange body color, had formed the white stripe at the nape, and began thigmotaxis (association with a solid object). At this point the fish could be netted and transferred to a grow-out aquarium.

The larval tanks were rather small, 36 gallons, and were designed to provide the proper environment for the newly hatched larvae. Temperature, lighting, salinity, and water quality were all considered in establishing the larval tanks. The design of the tanks also allowed development of water currents and micro-turbulence that aided floatation of food and larvae. The larvae were fed all live foods while in the larval tanks. Specially processed wild plankton and cultures of micro-organisms were the first food and after three days the larvae were large enough to accept brine shrimp and particulate dead and dried foods.

Growth of the larvae was quite fascinating. The disparity of growth rates among larvae from the same spawn that apparently had equal opportunity to feed was quite large. A few of the larvae entered the post larval stage within 5 days, the majority were at this point of development in 8 days and a few took 15 to 18 days before they gained color and abandoned their pelagic mode of life. This great variance in larval growth rate may be more pronounced in nature and may have bearing on distribution of Amphiprion in the Indo-Australian Archipelago- Philippines region. Those larvae that pass quickly through the larval stages would settle near the place of spawning while those with an extended larval life may settle far from their place of origin. There was no apparent difference in viability between the fast and slow growing larvae.

Juvenile Growth

When the majority of the larvae reached the post larval stage, about 10 days after placement in the larval rearing tank, they were removed and placed in an established 20 gallon aquarium to gain in size before being transferred to a 60 gallon grow out tank. At this time they were fed a formula similar to that fed to the adults but processed so that it would break up into many fine particles upon introduction to the tank. Newly hatched brine shrimp were also fed. The fry reached lengths of ½ inch in three weeks and many are about an inch long at an age of 6 weeks. There are no signs of malformations due to malnutrition or any parasitic infections. The fry are very alert and active and even began intraspecific behavioral interactions in the early post larval period. There was one small anemone in the first juvenile tank and the newly introduced post larvae quickly (within two hours) occupied the anemone. I did not observe any period of acclimation by the small fish to the anemone. There was no noticeable avoidance reaction by the fish when it first touched the anemone, however, the post larvae spent up to an hour drifting about the edge of the anemone before entering among the tentacles.

Eight to ten of the larger post larvae established territories on the face of the anemone and guarded this area vigorously. The largest, most dominant fish occupied the center of the anemone. At night these territories disintegrated and at least 50 small clownfish would enter the anemone and nestle among the tentacles. An interesting coloration abnormality occurred in about 10% of the fish. The center stripe, which forms at about 10 to 15 days of age, does not form completely. In some fish only a dorsal saddle is present and in others the bar is incomplete on one or both sides. One fish, a runt, had only one small oval white spot on the right side instead of a mid-body band. There is a tendency for the abbreviated band to develop toward normalcy as the fish ages, but as of this writing none of the markedly brief bands have become completely normal. This unusual banding usually occurs among the fastest growing fish, although there are exceptions. It may be that the period of band formation is somehow disrupted by the rapid larval growth than the tank reared larvae experience.

The black edging of the pelvic fins are the first black areas to develop. The largest juveniles are now displaying the black edging on the caudal and soft dorsal fin. The white band about the caudal peduncle is the last white band to develop and this is usually in evidence at about 15 days.

Many problems remain to be solved (some haven't even been identified) before breeding marine tropical fish becomes routine. However, the successes reported in this brief article indicate that production of large numbers of marine tropical fish is possible. The very basic technology has been developed and given the proper facilities and development time, I feel that many species could be cultured. The basic principles are adaptable to other species, certainly to other Amphiprion, but I am sure many specialized problems will be encountered with various species. The fish from these experimental spawns are now on display at Scott's Highway Aquarium in St. Petersburg, Florida. I hope future articles will be able to recount additional successes and perhaps more details on spawning and rearing procedures.

References

1. Allen, G. B. 1972. Anemonefishes, their classification and biology. T.F.H. Publications, Inc. LTD, Neptune City, N. J. : 1 - 288 pages.
2. Meulengracht-Madsen, J. 1071. Breeding Amphiprion percula. Tropical Fish Hobbyist, Vol. XIX, March 1971: 52-57.
3. Neugegauer, W. 1969. So zuchen wir Korallenfische. Aquarien Macazin. Stuttgart, Dec. 1969: 483-488.
4. Schreiner, W. 1972. Breeding Report Clownfishes. The Marine Aquarist. Vol. 3, No. 31-33.

 

Breeding the Clownfish, Amphiprion ocellaris, postscript

The sixth spawn was also infected with the parasite within the eggs, however, only a portion of the spawn was lost. The eggs were removed from the parents a few hours after spawning and were treated in a solution of sulfathiazole and quinine for three hours. They were then artificially incubated in a methylene blue solution for the entire 8 days of development. The presence of the parasite was noted on the evening of the fourth day of incubation and on the fifth day 330 infected eggs were removed from the rock. Four more were removed the following day and the remaining eggs seemed to develop normally. About 200 eggs remained and hatching took place on the evening of the eighth day. Not all the eggs hatched, about 50 remained on the rock and were expected to hatch the following night. At this point, I made an error. The tank was not adjusted to the larval rearing condition because the remaining eggs were still incubating and about 50% of the newly hatched larvae were lost. Most of the remaining eggs did not hatch anyway, thus all the trouble and loss of larvae was unnecessary .Good experience was gained, however, and about 50 strong larvae resulted from the sixth spawn. Even in larvae 48 hours old, remarkable size variation occurs. Some of the larvae are already 6 mm long and beginning to develop orange coloration while others are still the size of a newly hatched larva.

There is a considerable amount of variation within the subfamily Amphiprioninae, the clownfishes. These fishes are customarily divided into five groups, or species complexes. These include (in descending order with respect to number of member species) the Clarkii Complex, the Skunk Complex, the Tomato complex, the Saddleback Complex, the Percula Complex, and the Maroons. Of these, the first three were each discussed in preceding parts of this series. This part will focus on one of the smaller, and certainly lesser known, of these groups, the Saddleback Complex.

The Saddleback Complex has only three member species, namely the wide-band clownfish, the saddleback clownfish, and the sebae clownfish. Each of these bears white bars or stripes; these markings often appear as saddles across their backs. Clownfish of this complex are typically very dark in color, having predominantly brown or black base coloration, perhaps with highlights of yellow and orange. They are somewhat larger and more slender in shape than most other clownfish. Many aquarists seem to agree that there is something about the overall appearance and behavior of these fishes that soundly conveys their delicate nature and exotic provenance.

All things considered, clownfish of this species complex are among the most problematical to maintain in captivity. From the time of purchase, specimens may suffer from trauma associated with acute shipping stress. They are particularly susceptible to ailments and crippling physical conditions (e.g., pop-eye). They are not particularly quick to adapt to life in enclosed spaces; especially at night, movement around the aquarium can send these skittish fishes crashing into the glass panels or even leaping from the tank altogether.

A considerable amount of planning and resources will be required of those who hope to successfully keep, much less breed, fishes of the Saddleback Complex. While it could be said that all new acquisitions should be quarantined prior to introduction into a display, it is certainly wise to allow a period of isolation/adjustment for these fishes. During this period, the animals should be observed often, but disturbed as little as possible.

An emphasis should be placed on the type of enclosure that will be used. Recommended features of aquaria containing fishes from this complex include:

• A size of 40 gallons or (preferably) more.
• Aquascaping that includes plenty of shelter, as well as wide, empty spaces through which individuals can dash if startled.
• A lighting system that gradually increases/decreases intensity of illumination (rather than suddenly turning completely on or off).
• A hood that is secure enough to prevent escape.
• Placement of the quarantine system, as well as the main system, in a low traffic area.

At present, these species are very much underrepresented in the ornamental fish trade. This is due mainly to the locales from which they are collected. In the case of the wide-band clownfish, collectors do not frequent its extreme southerly range (some of which is protected); in the case of the saddleback clownfish and sebae clownfish, collectors tend to pass over the relatively unproductive sandy/silty flats where they mainly occur.

It seems that this vacuum in the trade is being filled by "imposter" fishes; for instance, while there is a ready supply of specimens being offered as Amphiprion sebae, many of these are actually misidentified members of the Clarkii Complex. Particularly because identifications made by dealers are often less than dependable, it can be of great value to the aquarist to be aware of the distinguishing characteristics of each of these species.

The Saddleback Complex in profile

Wide-band clownfish (Amphiprion latezonatus Waite, 1900)

The Wide-band clownfish is found on cooler rocky and coral reefs from the eastern coast of Australia to New Caledonia and the Lord Howe Island group (subtropical). It is typically associated with the sea anemone Heteractis crispa. Wild specimens of this species are rare in the trade, and captive bred specimens are perhaps even rarer. For reasons that are not yet completely clear, captive bred wide-band clownfish are frequently misbarred (a trait which is, at least in the case of this species, generally considered to be undesirable). It is distinguishable by its blue "mustache," its very dark base color, and its very broad mid-body stripe. It reaches a maximum length of 14 cm.

Saddleback clownfish (Amphiprion polymnus Linnaeus, 1758)

The saddleback clownfish occurs in sediment-rich inlets and lagoons from Northern Australia and New Guinea to Southeast Asia (tropical). It is typically associated with the sea anemone species Heteractis crispa and Stichodactyla haddoni. The saddleback clownfish is available in two strains. The "common" strain bears a white head stripe and mid-body stripe (which is usually saddle-like) with a yellow to orange face, pectoral fins, and ventral area. Individuals from New Guinea may have much orange in the ventral area. The "black" strain is very dark-bodied but with bright yellow highlights. Both strains reach a maximum length of 13 cm.

Sebae clownfish (Amphiprion sebae Bleeker, 1853)

The "true" sebae clownfish is native to shallow waters of the Indian Ocean from the Arabian Peninsula to India and Sri Lanka to parts of Indonesia (tropical). It is typically associated with the sea anemone species Stichodactyla haddoni; interestingly, it is not typically associated with the so-called sebae anemones Heteractis crispaand Heteractis malu. With its saddle-like mid-body band and yellow-orange face and ventral area, it can be quite similar in appearance to Amphiprion polymnus. It is distinguished by having the most and brightest yellow-orange coloration (though specimens from Bali can be quite dark). It is the largest member of the complex, reaching a maximum length of 16 cm.

Conclusion

Members of the Saddleback Complex are among the most challenging species of clownfish to maintain in captivity. A rather high level of care must be reached to ensure (if it can be ensured) the health and wellbeing of these sensitive animals. Generally, attempts to keep these fishes should be undertaken by advanced aquarists (especially so if host anemones are to be kept as well).

Properly cared for, the wide-band clownfish, the saddleback clownfish, and the sebae clownfish alike will undoubtedly enhance the beauty and distinctiveness of any marine aquarium display.

References

1. Wilkerson, Joyce D. Clownfishes: A Guide to Their Captive Care, Breeding, & Natural History. Shelburne, VT: Microcosm Ltd., 1998.
2. Fautin, Daphne G. and Gerald Allen. Anemonefishes and Their Host Sea Anemones. Morris Plains, NJ: Tetra Press, 1994.
3. Skomal, Gregory B. Clownfishes in the Aquarium. Neptune City, NJ: T.F.H. Publications, Inc., 2004.
4. http://fishbase.org
5. http://www.sustainableaquatics.com