One of the foremost objectives in re-circulating aquaculture is to maintain system stability. This is not wholly unreasonable in light of the fact that 1) our closed systems can be inherently prone to sudden and devastating disturbances (i.e., "crashes"), and 2) a great many aquatic organisms depend upon a certain degree of environmental stability for their survival and reproduction (Riddle, 2009). One may further suppose that long-term stability, in allowing for full ecological succession, promotes species richness; however, evidence from a growing body of ecological field investigation continues to suggest that this is not always so.

Until the early 1960's, most experimental evidence of interspecific competition was derived from the observation of laboratory animal populations under more or less static laboratory conditions. Where the indirect influence of competitive interaction among natural communities was not self-evident, the role of competition in community organization was customarily overlooked. By the early 1970's, numerous researchers in the rapidly expanding field of community ecology (which emphasizes structural characteristics and relies heavily upon interpretation of field data) were eager to demonstrate that biological communities are not merely isolated clusters of populations, but highly dynamic, interconnected systems with multiple levels of order.

A characteristically dense aggregation of sea palms (Postelsia palmaeformis) on a newly exposed rock face. Photo courtesy ofMendocino Coast Botanical Gardens.

A considerable breakthrough was made on their behalf with the publication of Paul K. Dayton's highly influential demonstration (1971) of the competitive interactions that occur among sessile marine organisms following major disturbance events. This important work served, and continues to serve, as the basis for numerous other researchers' efforts to develop a general theory of disturbance (Sebens 1984).

In 1) reviewing a selection of studies that were influential in the development of ecological disturbance theory, and 2) describing marine hard-bottom community structures in the context in which they served as experimental and theoretical subjects, this article seeks to call attention to the implied (albeit strong) relevance of disturbance theory in the culture of marine ornamental species. Though the investigations herein described were conducted on natural populations, the models are intended to be universally applicable; hence, they are theoretically analogous to the competitive interactions of sessile organisms in all disturbed hard-bottom communities--whether between macroalgae and juvenile farm clams on a freshly-scoured net pen, between tropical sponges and corals after a sustained influx of sediment over a reef, or between microorganisms on the human tooth after a good flossing.

1. Introduction

Temperate rocky intertidal habitats are among the earliest and most thoroughly studied biological communities by field ecologists. It remains firmly established that the lower intertidal zone is typically dominated by flora with a distribution determined most directly by biotic factors (e.g., competition for light, resistance to herbivory), while the upper intertidal zone is typically dominated by sessile fauna with a distribution determined most directly by physical factors (e.g., heat, desiccation, wave exposure, battering by drift logs) (Connell 1961; Dayton 1971; Nielson 2006). Evidence from earlier studies (Connell 1961) convinced Dayton (1971) that disturbance indirectly reduces the intensity of competitive interactions in the upper intertidal zone, and that species richness is greatest in environments subject to intermediate levels of disturbance. In so doing it resulted in the development of a mechanism (Dayton 1971) that seemingly contradicts presumptions (McNaughton and Wolf 1970) that competitive dominance is typified by abundance, that dominance is strongly correlated by broad niches, and that species attain membership in communities by increasing carrying capacity or narrowing niches (or both).

To avoid wide dispersal, mature sea palm sporophytes such as these only release spores during low tide emersion; spores simply drip from deep grooves in their blades onto the immediate vicinity. Photo by Lyudmila Zinkova.

As of late, ecological research in this area usually 1) describes patterns of abundance/distribution of sessile organisms, 2) explains how these bands of distribution arise from the various community members' responses to various physical pressures, and 3) experimentally demonstrates how abrupt temporal (including seasonal) and spatial discontinuities in distribution arises from interspecific competition (Dayton 1971; Sousa 1985; Blanchette 1996).

The rocky shores of the Northeast Pacific Ocean provide an ideal setting to study ecological succession and the effects of disturbance regimes; not only are they reasonably accessible, but they are experimentally amenable in that they are geographically unbroken with flora and fauna that have overlapping ranges that are confined to the intertidal zone. These communities are open-ended, as most primary production and decomposition takes place elsewhere (Dayton 1971). Furthermore, a great majority of interspecific competitive interaction involves the struggle to claim space, which is relatively simple to analyze in this environment, owing to a two-dimensional substrate and clearly delineated bands of vertical distribution (Dayton 1971).

Garden-variety models of competition predict that, under static environmental conditions, a single species would effectively dominate in each intertidal zone. That being said, field evidence indeed suggests that certain stochastic disturbance events (particularly those that result in the localized clearing of habitable space) actually serve to promote species richness (Dayton 1971; Blanchette 1996). Identifying factors that influence community succession may be critical in describing the path to dominance under circumstances where habitable space is likely to be a limiting resource (e.g., high-density monoculture). Processes that drive community organization cannot, in these cases, be fully explained without evaluating the disturbance regimes that relieve pressure for space (i.e., allow coexistence).

Sea stars (Pisaster ochraceus) taking refuge in the shade during a low tide. Evidence of sea star predation can be observed in the nearby mussel bed (Mytilus californicus). Photo by Kenneth Wingerter.

In Northeastern Pacific littoral habitats, monopolization of space is prevented by both biological and physical disturbance. Biological disturbance results mainly from the activity of limpets, gastropods, and starfish on barnacles, mussels, and kelps. Physical disturbance results mainly from wave action and impacts with floating logs (Dayton 1971). The most important ecological function of these periodic disturbances is the clearing of primary substrata, which may immediately be recolonized. Within this setting, competitive dominants ultimately claim all available space at low disturbance rates, whereas superior colonizers claim all available space at high disturbance rates; coexistence occurs at intermediate disturbance rates. (Sebens 1984).

As theoretical ecologists have moved away from approaches that are preoccupied with equilibrium, the role of spatial heterogeneity in models of population dynamics has received greater attention (Nielson 2006; Sebens 1984). In these models, patches of primary substrata are treated as fundamental structural units; patterns of spatio-temporal heterogeneity emerge with increasing regional scale. Patches are taken to be a "holes" in an otherwise homogeneous reference background. Though bounded and discrete, they are not viewed as closed systems, but rather as individual components of a larger spatio-temporal mosaic. The random colonization and founder effects that follow natural succession regimes guarantee the ongoing integrity of this larger system. At least certain species in these communities depends upon certain levels of local disturbance (Levin and Paine 1974).

2. Typical Field Composition

Ecological succession usually leads to dominance by mussels (Mytilus spp.), which tend to displace barnacles (Balanus spp. and Cthamalus spp.) and have a negative influence on the recruitment of sea palms (Postelsia palmaeformis). Mussels quickly claim primary substrata. Subsequent mussel recruitment results in multilayered colonies that become increasingly threatened with disruption by wave action as they grow (Dayton 1973; Sousa 1985). Attacks by starfish (Pisaster ochraceus) and beatings by drift logs disrupt the continuity of mussel beds, thereby increasing their susceptibility to damage from wave shock. Small clearings become enlarged as newly exposed mussels are ripped away at the edges (Dayton 1971; Dayton 1973).

A markedly different community can be observed only a couple meters away in calmer, landward-facing tidepools; this community is dominated by sea anemones (Anthopleura xanthogrammica), serpulid tube worms, and red algae. Photo by Kenneth Wingerter.

Significant changes in community structure are usually not brought about by either periodic or stochastic episodes alone; it indeed seems that a combination of these effects are necessary (Liddel 2001). Although it is nearly impossible to differentiate between patches cleared by starfish from those cleared by wave shock, recovery is usually more rapid in the lower intertidal zone (where mussels are more susceptible to starfish) than in the upper intertidal zone (where they are more susceptible to drift log impact). Damage from logs tends to be seasonally punctuated by winter storms, while damage from starfish predation occurs steadily.

The extent of direct wave exposure of the site also seems to influence the initial patch size, helping to vary the size and degree of disturbance from patch to patch. Expressed as percent of original cleared substrata, the mean increase in size of initial patch size has been found to range from 24-4,884% (Dayton 1971; Dayton 1973). In recent models, attempts have been made (Liddel 2001) to account for spatio-temporal patch variability on species richness.

The race to invade disturbed marine hard-bottom habitat is intense. Following a major disturbance, the activity of limpets foraging on the newly cleared patch creates a minor disturbance by dislodging recently recruited mussels. Thus, by feeding on limpets as a secondary prey item, starfish have a direct positive effect on the growth of its preferred prey. In the total absence of starfish predation, mussels (owing to their higher growth rate) eventually dominate other sessile community members for space (Dayton 1971). Mussels are not only slower recruiters than barnacles, but are less successful at settling on bare rock, preferring instead to settle onto--and eventually outgrow--barnacle encrustations. Barnacles thusly often get first crack at freshly cleared substrata, with Balanus dominating Chtamalus in all but the uppermost intertidal zones, where it succumbs to physical stress. Further barnacle invasion is accelerated as additional recruits are stimulated to settle near conspecifics already attached to the surface; intraspecific competition is rather minimal (Connell 1961).

Mussels prefer to settle onto barnacle encrustations (as opposed to bare substrata), and may eventually smother a barnacle colony; however, barnacles can invade invader, later resettling onto mussel shell parts. Photo by Darkone.

Field investigation has suggested that sea palms, while preferring to settle on bare rock, are not only weaker dispersers than are barnacles, but have a narrow reproductive season (notably during winter storm season) (Paine 1988). As an annual kelp, Postelsia is a particularly weak disperser (Dayton 1973; Paine 1988; Nielson 2006). Postelsia has a conspicuously aggregated distribution; its growth habit results in structures that are rather clumped, with sporophytes growing on the holdfasts of older individuals (Dayton 1973; Kusumo 2006). Genetic relatedness between individual sea palms within a single cluster has been shown to be strikingly high (Coyer 1997). As with barnacles, intraspecific competition among sea palms appears to be minimal; indeed, the larger a population size is in a given area during year x, the greater are its odds of persistence into year x+1 (Paine 1988).

3. Discussion of Models

All relevant variables of disturbance (including frequency, magnitude, and size) should be accounted for in any disturbance theory that proposes a testable hypothesis and can consistently make useful predictions. Any such predictions should relate directly to the disturbance variables and response parameters (Dayton 1971; Pickett 1985). Response parameters that are most vital to community structure can be determined by experimental field manipulation (removal of predators, etc.) after rates and patterns of succession are identified (Dayton 1971). Due to the uncertainty inherent in the very process of stochastic disturbance itself, the greatest difficulty in developing a general disturbance theory lies in accurately accounting for particular factors that modify responses in certain contexts. The special character of a single disturbance event may be defined by factors such as landscape shape/composition, system structure (i.e., degree of connectedness in relation to the substrate), resource base, life histories of the component populations, and site-specific competitive dynamics (Pickett 1985).

The model presented by Paine and Levin (1974) was significant not only in that it was a direct answer to Dayton's influential mechanism (1971), but also in that it was held to be applicable to systems outside the realm of marine hard-bottom biotypes; assemblages of patches are treated as one would treat an assemblage of cells, with each distinguished by its age and size. With the development of this input-output model, Paine and Levin sought to relate the distributional properties (particularly with regard to age and size) of disturbed patches to the biological properties of the invading species.

Armstrong (1976) pointed out that the Paine-Levin model placed an undue emphasis on patch structure, while trivializing differential abilities of the invaders to settle on and compete for primary space. The "fugitive species model" he developed expressed these differences in an effort to better describe patterns of biodiversity as they emerge in disturbance-facilitated community organization.

Hastings (1980) attempted to build upon earlier models by accounting more realistically for the effect that the number of competing species and their relative abundances have on coexistence. Biodiversity is here simply calculated as a function of percent coverage of substrata. The type of competitive interaction this model is meant to best represent is that for space on a hard surface where space is the limiting resource. It predicts that the type of competition and rates of colonization are far more consequential in the development of community structure than are any specialized interactions between component species. While this model proved to be more objective and, through its treatment of competitive hierarchy, offered more detailed predictions, it was (admittedly) over-simplified; not only did it lack accountability for recruiter priority effect, but it failed to demonstrate how a single competitor can dominate at levels of intermediate disturbance. Furthermore, the effect of disturbance (whether physical or biological) is administered at a fixed rate, acting upon populations of all species equally--a scenario that is unrealistic in both natural and even captive conditions.

Implementing a periodic disturbance regime may help to promote diversity (i.e., discourage dominance) within sessile invertebrate populations, as in this crowded Oceanário de Lisboa coral reef exhibit. Photo by Csörföly D.

Polycultureof sessile marine invertebrates may demand some understanding of disturbance-facilitated coexistence. Photo by Daben 2000.

Allowing for variable outcomes was a principle concern of Sebens (1984) in the development of an "indeterminate coexistence" model. Here it is acknowledged that there is a certain level of unpredictability in the outcome of competitive interaction between individuals of two different species--that is, species identity alone cannot guarantee the outcome of interspecific competition between individuals. In some competitive encounters, size or stage of settlement may convey a greater advantage than species identity. Sufficient numbers of these "reversals" are capable of locally disrupting competitive hierarchies. These reversals are now known to be rather common during competitive interactions for space in marine hard-bottom habitats (Sebens 1984). In one example, sea palms can gain a foothold in seral communities by settling on and displacing young mussel beds (where they settle on the shells of their competitor, sufficiently increasing the drag of wave action on their unwilling hosts, eventually causing them to be ripped from the rock (Dayton 1971; Dayton 1973).

In this model, non-competitive mortality is the result of physical or biological disturbance where a certain fraction of individuals is removed, while intrinsic mortality rates are considered to be insignificant. N₁, B₁, and D₁ respectively are per patch population size (number), recruitment (birth) rates, and disturbance (patch death) rates for Species 1, while K is a per patch carrying capacity. In a system with two competitors, mortality of individuals of Species 2 from competitive interaction with Species 1 is equal to the recruitment rate of Species 1 (B₁N₁/K per patch) multiplied by the population size of Species 2 (Sebens 1984).

dN₂/dt = B₂N₂ (K-N₁-N₂/K)-D₂N₂-B₁ (N₁N₂/K).

The range of disturbance rates at which coexistence may occur increases with larger difference of recruitment rates among competitors; such is the case where competitive hierarchies are rigid and well defined. This model utilizes additional terms for cases involving encounters where competitive success is indeterminate, probability f_ij, where the term (1-f_ij)N₁ is the approximate number of spaces j does not take from i per unit time (Sebens 1984).

(dN_i/dt)(1/N_i) = B_i(K-N_i-((1-f_ji)N_j)/K)-D_i-(B_jN_j/K)f_ij.

This can be simplified and given as the equation for each competitor.

(dN₁/dt)(1/N₁) = (B₁/K)(K-N₁-N₂+f₂₁N₂)-D₁-(B₂/K)N₂f₁₂.

(dN₂/dt)(1/N₂) = (B₂/K)(K-N₁-N₂+f₁₂N₁)-D₂-(B₁/K)N₁f₂₁.

If D = D₁ = D₂, the resulting two inequalities below define the upper and lower boundaries of D. Coexistence of two competitors is possible within this range.

Only the superior recruiter persists above some maximum difference in growth rates by dominating the other in some fraction of encounters. This advantage is magnified by the larger recruitment rate. For some value of B₁, let B_2max be the maximum value at which coexistence is possible at any rate of disturbance. Then where D_max=0, B_2max=B₁(f₂₁/f₁₂) . This can be interpreted to mean that domination is reversed between competitors with increasing disturbance rates. In the absence of this occurrence, competitors may coexist at any disturbance rate greater than D_min so long as it remains lower than the recruitment rate of the competitive dominant. Where competitors have similar recruitment rates, coexistence is only possible if fluctuation of disturbance rates is minimal. Such reversals of competitive success are credited for delaying competitive exclusion, and may allow the prolonged coexistence of competitors in systems that are subjected to highly stochastic disturbance regimes (particularly where there are large differences in recruitment rates). In applications that evaluate the competitive dynamics of multiple species, a single species may come to dominate a patch at intermediate disturbance levels; this was not a possible outcome in earlier models, though it clearly occurs in nature (as observed in patches dominated by Postelsia) and apparently in aquaria (e.g., Aiptasia plagues). In these cases, the competitive dominant may not necessarily be at the top of the competitive hierarchy, but is the best competitor that can persist under the current disturbance regime (Sebens 1984).

4. Conclusion

It is now widely accepted among theoretical ecologists that periodic, severe, localized environmental disruption can increase biological diversity. However, many of the processes by which this takes place are not yet fully understood. Ongoing research in this area will continue to be of particular benefit to government fisheries resource managers as well as producers of sessile marine fauna (e.g., coral farmers). A comprehensive understanding of how ecological disturbance influences biological community structure and diversity could aid considerably in carrying out stock assessments (as in efforts to minimize the ecological impact of wild harvest for the aquarium trade) as well as operational planning for intensive re-circulating aquaculture operations.

References

1. Armstrong, Robert A. 1976. Fugitive species: Experiments with fungi and some theoretical consideration. Ecology vol. 57, no. 5: 953-963.
2. Blanchette, Carol Anne. 1996. Seasonal patterns of disturbance influence recruitment of the sea palm, Postelsia palmaeformis. Journal of Experimental Marine Biology and Ecology 197: 1-14.
3. Connell, Joseph H. 1961. The influence of interspecific competition and other factors on the distribution of the barnacle Chthamalus stellatus. Ecology vol. 42, no. 4: 710-723.
4. Coyer, James A., Jeanine L. Olsen and Wytze T. Stam. 1997. Genetic variability and spatial separation in the sea palm kelp Postelsia palmaeformis (Phaeophyceae) as assessed with M13 fingerprints and APDS. Journal of Phycology 33: 561-568.
5. Dayton, Paul K. 1971. Competition, disturbance, and community organization: The provision and subsequent utilization of space in a rocky intertidal community. Ecological Monographs vol. 41, no. 4: 351-389.
6. Dayton, Paul K. 1973. Dispersion, dispersal, and persistence of the annual intertidal alga, Postelsia palmaeformis Ruprecht. Ecology vol. 54, no. 2: 433-438.
7. Hastings, Alan. 1980. Disturbance, coexistence, history, and competition for space. Theoretical Population Biology 18: 363-373.
8. Kusumo, Handojo T., Catherine A. Pfister and J. Timothy Wootton. 2005. Small-scale genetic structure in the sea palm Postelsia palmaeformis Ruprect (Pheaophyceae). Marine Biology 149: 731-742.
9. Levin, Simon A. and R. T. Paine. 1974. Disturbance, patch formation, and community structure. Proc. Nat. Acad. Sci. USA vol. 71, no. 7: 2744-2747.
10. Liddel, Michael. 2001. A simple space competition model using stochastic and episodic disturbance. Ecological modelling vol. 143, issues 1-2: 33-41.
11. McNaughton, S. J. and L.L. Wolf. 1970. Dominance and the niche in ecological systems. Science 167: 131-142.
12. Nielsen, Karina J., Carol A. Blanchette, Bruce Menge and Jane Lubchenco. 2006. Physiological snapshots reflect ecological performance of the sea palm, Postelsia palmaeformis (Phaeophyceae) across intertidal elevation and exposure gradients. Journal of Phycology 42: 548-559.
13. Paine, R. T. 1988. Habitat suitibility and local population persistence of the sea palm Postelsia palmaeformis. Ecology vol. 69, no. 6: 1787-1794.
14. Pickett, S. T. A. and P. S. White. 1985. The Ecology of Natural Disturbance and Patch Dynamics. Patch dynamics: A synthesis. Chap. 21: 371-384.
15. Riddle, Dana. 2009. Environmental Stability: A Comparison of a Natural Reef and an Aquarium. Advanced Aquarist's Online Magazine, Volume 8, Book 1: 2009 Edition. Pomacanthus Publications, Inc.
16. Sebens, Kenneth P. 1984. Competition for space: Effects of disturbance and indeterminate competitive success. Theoretical Population Biology 32: 430-441.
17. Sousa, Wayne P. 1985. The Ecology of Natural Disturbance and Patch Dynamics. Disturbance and patch dynamics on rocky intertidal shores. chap. 7: 101-124.

My system consists of just over 335 gallons including a 247g SPS dominated display, a 50g chalice frag tank, and a stock 75g sump. I run just about every type of lighting that is offered in this hobby. This includes a Sfiligoi 72" XR6 over my display and an ATI 10 x 39w Powermodule with a 36" ReefBrite LED strip over my chalice frag tank. Calcium / Alkalinity are dosed via a Litermeter III using Bulk Reef Supply's 2-part system. My skimmer is a Royal Exclusiv AlphaCone 300. The sump contains water, a skimmer, a heater, and a powerhead - very clean and simple. While the basis of my system is quite simple, I do really enjoy the technical side of this hobby. I have some equipment that is necessary in this hobby and some that a lot of reefers will consider luxuries. In this article, you will see several examples of both. If there are 100 ways to keep a successful reef ecosystem, I have likely tried 90 of them. And while there is not a perfect method for everyone, there are some fundamental similarities with all of the beautiful systems that we all read about. I'll get to that in a minute. But first, let talk about what got me here...

Oooooh...what is that called?

March 29, 1997 - I walked into Fishy Business in Columbia, SC and I was hooked within seconds. Like any newbie to saltwater, I asked a thousand questions and walked away with a thousand more. I ended up buying a 75g tank that belonged to one of the LFS employees about 2 weeks later. The system looked amazing to me. Well established live rock, the old school halide pendants with ballasts that weighed about 50 pounds each, and a simple sump setup. Piece of cake right? Yeah! I probably spent at least 2 hours a day at the LFS for the next 3 months asking every question in the book. The guys in the shop were very patient and they taught me quite a bit about the hobby. However, I learned on the go which, in this hobby, is not always the best way. But I learned many valuable lessons that would come in handy years later. I'm not going to waste any time on that first tank. I moved 8 times in 6 years and you can imagine the toll it took on the tank and its inhabitants. I was out of the hobby for a number of years but came back armed with a lot more knowledge.

Undisputed Champion of "Can't leave well enough alone" - not as prestigious as it sounds

Fast forward almost 10 years - ten years of reading every reef book, every thread on every website I could find, and visiting every LFS in every town I lived in. I felt like I was better educated in proper reef-keeping techniques. My wife and I walked into Fish World in Richmond, VA and I instantly got the bug again. I had met Joe Genero (owner) years before and loved the store that he and his wife Jan had built over the years. They were the first LFS in the nation to go all saltwater over 20 years ago. Joe helped me design a system that I would love. I had a laundry list of things that I wanted and didn't want. We are lucky to have an unfinished basement in our house. Both the main water line and main house drain are down there and there is tons of space that we really don't use. We went with a 150g Tall AGA and decided to place the sump and equipment in the basement - just below the tank which sits on the main floor. The tank came with a blue vinyl background, a nice stand and canopy, 2 14K 400w halides, a stock 75g sump with a refugium, a UV light, some moonlights, and a Reef Octopus skimmer. I spent the next few months stocking up on corals and fish and everything was doing very well. But my A.D.D. and (non-diagnosed) OCD kicked in and I started tweaking here and there to try and make things even better. I'm not proud of this, but here is a list of changes I made over the next 3 years (bear with me):

• Added 4 T5's to add some extra pop to the corals
• Started the Prodibio system - stopped after a few months
• Took off the blue vinyl background and painted the back of the tank black (on the outside of course)
• Bought a chiller as the halides were heating up the water
• Got a calcium reactor - got tired of manual dosing
• Decided to switch to all T5's as the power bill was getting outrageous - removed canopy for open top
• Sold the chiller since I didn't need it any longer
• Bought a bigger skimmer
• Started dosing vodka / Microbacter 7
• Took the refugium out of my sump - was a nitrate factory with the sandbed
• Got rid of the calcium reactor as I couldn't keep it dialed in - Alk was all over the place
• Switched to 2-part dosing (Bulk Reef Supply)
• Stopped dosing vodka / MB7 as my corals were starving
• Completely changed aquascape...twice...lol.
• Added frag tank

As embarrassing as all of those changes are, I feel like it's important to share them. Every time I saw a 'Reef of the Month' that I loved, I wanted to apply some of that success to my tank. Keep in mind, I was NEVER careless with the changes. Lighting changes were made very slowly as to not shock the corals, vodka dosing was done according to plan, etc. Surprisingly, I didn't lose any corals and all of my livestock thrived through all of the changes. My point is...it is VERY easy to get caught up in the latest and greatest thing. However, at the end of the day sometimes simplicity can produce the best results.

What did you just say?

My 150g had been up and running for just over 3 years, SPS was growing very well, fish were getting larger, and the tank was starting to fill in. My wife and I were watching TV one night and she looked over and said "I think we need a bigger tank"! I couldn't believe it. Being the wonderful husband that I am, I immediately called my good friend Andrew and said "I need your help fast - before she changes her mind". I knew the exact tank dimensions I wanted and Andrew had a mockup hand-sketched drawing of the stand within hours...lol. I decided to go with a 247g (72" x 33" x 24") Miracles Rimless - peninsula style tank with ¾" glass - Starphire on 3 sides. When Derek at Miracles told me that it was going to weigh 700lbs empty, I about died. Time to reinforce the floor : ). My goal with this tank build was to design a system that took all of the headaches out of the hobby (or as many as possible). I also wanted a stand that was completely different from anything I had ever seen. I travel 3+ days per week for work so I had to have a system that would be easy to maintain in my absence and easy for my wife to manage while I travel. My LFS (Fish World, Richmond, VA) helped me eliminate many of these headaches. I have 1 pump for the entire system which feeds my display, frag tank, carbon & GFO reactor, and pushes waste water to the house drain for water changes. We installed a 60g fresh water vat for top-off and a 100g vat for saltwater mix up. Water changes take me 5 minutes and I barely have to lift a finger. My LiterMeterIII handles Alkalinity, Calcium, and fresh water top-off. The only equipment in the sump is my skimmer, a heater, and a Tunze to help keep detritus from settling. My old 150g tall was a great tank but I had to use a step ladder to do just about everything. The 24" height of the new tank is great as I can actually reach things in my tank now. My friend Andrew helped me design and build a one-of-a-kind stand to hold the new tank. Okay, so he pretty much built the whole thing. I was just there to lend a hand : ). The bones of the stand are fairly standard (4x4's, cross braces, etc. - it could hold 10 tons I'm sure). We finished the outside of the stand with "Tahitian Pebbles" and a few access panels for storage and maintenance. It turned out even better than I ever imagined and I couldn't have done any of it without Andrew (thanks again my friend). It is truly one of a kind and I love it!

How do I pick a light for this thing?

I used T5's exclusively for 2 years over my 150g and had excellent results. For the new display, I did a LOT of research! I spoke with just about every lighting manufacturer you can imagine. I ran a Sfiligoi Stealth 12x54w T5 fixture over my 150g and loved the build quality, active cooling, and reflector quality. I have gotten to know Tim Lasiter (NA Distributor for Sfiligoi - Aquatics Elite) well as I bought my original Stealth fixture from him. I discussed my needs with Tim and he was able to get a package together that met every need. I decided to go with a 72" Sfiligoi XR6 (3x250w 20K's with 8 x39w T5's). The fixture itself is a work of art. It is as pleasing to the eye as it is effective for my tank's inhabitants. I really wanted to be able to dim the halides and T5's. Sfiligoi had a great solution for that as well. I have 3 ACLS ballasts (1 Master and 2 Slaves) which allow me to control each halide independently. The functionality of these ballasts is incredible! I can dim each halide, simulate east / west sun patterns, program cloudy days, and it has a "new bulb function" that ramps up new halide bulbs slowly as to not shock the corals (just to name a few of the many amazing features). The T5's are hooked up to my Apex controller which allows me to dim each bank of bulbs as well. I didn't realize just how much I missed the "shimmer" until I started running halides again. The fixture is well vented without fans so I don't have to run a chiller again - which is fine with me. The corals have never been happier.

Time for the switch...

The 700lb tank took 12 men to get into the house. My wife left town as she was too nervous to watch...lol. The stand was completed a week before the tank arrived so all we had to do was get the tank on the stand and hang the light. Many hobbyists would take the next few weeks / months to get the new tank up and running. I have never been much good at going to bed with a project looming over me, so I stayed up for 3 straight days and nights once the tank arrived. At the end of the 3 days the light was up, the tank was full of salt water, and both the 150g and the 247g were all running online together. I ran both tanks together for 7 days to allow the existing water to circulate through the new tank. I used brand new sand (seeded with existing sand from my 150g), used all rock from my old tank (plus some new live rock), and got the corals transferred over the next week and a half. My SPS did surprisingly well in the move. I was able to keep the same 75g sump in the basement. The only real change I made in the "fish room" was a larger skimmer. I upgraded from the Royal Exclusiv Alpha Cone 250 to the 300. It's more than enough skimmer for my system.

I put a LOT of time, thought, and effort into this new system. Needless to say, I spent just as much time thinking about proper rock and coral placement. The new tank is SPS dominated with a few LPS thrown into the mix as well. I had an idea of how I wanted my aquascape to look - minimalist, with plenty of open room (negative space) for the fish to swim and (most importantly) for the corals to grow. One of the biggest mistakes I see new reefers make when stocking a tank is putting too much in the tank without giving any thought as to what it may look like in a year or two (this includes both rock and coral). Like other successful hobbyists, I now research all new coral purchases to see where to put the specimen in the tank. The aquascape is pleasing to my eye and the fish swim in and out of the "islands" just as they would naturally on the reef.

Obsessive Compulsive Disorder - can be a positive in this hobby ; )

While I have never been clinically diagnosed, anyone who knows me well will tell you that I have a problem! I have zero patience for nuisance algae, coralline algae on the glass / powerheads, aptasia, or anything else in my tank that is not supposed to be there. I spend a LOT of time observing my corals. I allow my corals to tell me when something isn't right with my tank. If I observe my corals lightening or if there is a small diatom bloom, I am able to catch it early, diagnose the issue, and respond accordingly. It took me YEARS to get to that point. I used to test my water every day. Since I've gotten better at identifying small issues, my daily testing regimen has decreased to once per month. Other than water testing, here is my basic maintenance schedule:

Daily

• Check plumbing connections (takes 2 seconds)
• Syphon any detritus from frag tank
• Observe each and every coral, fish, and frag in my system
• Clean glass of display, frag tank, and sump

Weekly

• Clean powerheads with vinegar bath
• Clean overflow "teeth"
• Check all bulbs to ensure everything is "firing" properly

Monthly

• 10% water change
• Clean entire skimmer / skimmer pumps
• Clean powerhead in sump
• Completely clean out frag tank (razor blades, toothbrushes, whatever it takes)
• Inspect bulkheads
• Clean overflow and return plumbing (Loc-line, PVC)

Every 6 months

• Replace bulbs as needed
• Clean main system pump

I take a proactive approach to tank maintenance. If I could give just a few pieces of advice to folks looking to take this hobby to the next level, this would be one of them. Of course there are always things in this hobby that you can't plan for (cyano blooms, bryopsis, etc.) but if you are persistent AND consistent in your tank husbandry, you will be rewarded down the road. Set a realistic course and stick to it!

Tank parameters

• pH 8.1 - 8.3 (pH probe monitored with Apex - I recalibrate my pH probe monthly)
• Calcium 475ppm (Salifert)
• Alkalinity 8.0 dKH (Salifert)
• Magnesium 1450ppm (Salifert / Elos)
• Salinity 1.025 (Milwaukee Refractometer)
• Nitrates 0.5ppm (Salifert)
• Phosphates Undetectable (Salifert)

Tank Equipment

• Display Tank - Miracles Rimless ¾" 3-side Starphire glass Peninsula style tank (72"x33"x24")
• Display lighting - 72" Sfiligoi XR6 (3x250w 20K SE Radiums & 8x39w T5's Actinic)
• Display tank powerheads - 2 Vortech MP60ES (wirelessly controlled through Apex WXM Module)
• Frag Tank - GlassCages 3-side Starphire glass tank (40"x30"x9")
• Frag Tank lighting - ATI 10x39w Powermodule & 1x36" ReefBrite LED strip
• Frag Tank powerhead - 1 Vortech MP40 (Gen 2)
• Main circulation pump - Reeflo Hammerhead
• Sump - 75g AGA tank
• Sump powerhead - Tunze 6201
• Skimmer - Royal Exclusiv Alpha Cone 300 (with Avast Marine Swabbie)
• Controller - Neptune Systems Aquacontroller Apex (2 DC8's, WXM, VMD, pH / temp probe)
• RO/DI Unit - Bulk Reef Supply 300gpd TDS Spartan
• Dosing - LiterMeterIII - Handles Alk, Ca, and Top-off
• Remote Monitoring - Canon VB Webcam (in basement to monitor guts of system)

Mineral Supplements

• Calcium / Alkalinity - Bulk Reef Supply 2 part (Recipe 1)
• Magnesium - Kent Tech-M (Manually dosed once per week)
• Carbon - Bulk Reef Supply Rox (changed every 2 weeks)
• PO4 Remover - Rowaphos (changed every 2-3 weeks)
• Iodine - Lugol's (3 drops per day)
• Zeovit Coral Snow - As needed for cyano blooms
• Salt - Tropic Marin BioActif

Lighting Schedule (Display)

• 10AM - 12PM: All T5's - 2 hour sunrise - 0%-80% (off 15 minutes after halides come on)
• 11:45AM-7:45PM: Halides ramp up from 0-100%, full power for 5 hours, and ramp down from 100%-0%
• 7:30PM - 10:30PM: All T5's - 3 hour sunset - 80%-0%

Lighting Schedule (Frag Tank) - Reverse schedule

• 9:00PM - 10:00: ReefBrite LED's
• 10:00PM - 11:00PM: 4 T5's (Super Actinics / Blue +'s)
• 11:00PM - 4:00AM: All 10 T5's on
• 4:00AM - 5:00AM: 4 T5's (Super Actinics / Blue+'s)

Livestock

Fish

• Tongan Sailfin Tang
• Yellow Tang (2)
• Yellow Coris Wrasse (2)
• Sixline Wrasse
• Flaming Hawkfish
• Block Anthias (2 -Mated pair)
• Chocolate Tang
• Majestic Angelfish
• Black Tang
• Kole Tang
• Hybrid Powder Blue Tang
• Mimic Tang (Indian Ocean)

SPS

• Tri-Color Prostrata
• TCN Royal Blue Tenuis
• ATL Forest Fire Acropora
• Skittles Granulosa
• Bubblegum Millie

• Blue Hokei
• Darth Maul Porites
• Tyree Pink Lemonade
• Tyree Meteor Show Cyphastrea
• ORA Chips
• ORA Hawkins Echinata
• ORA Red Planet

• ORA Borealis
• Tyree Setosa
• Tyree Superman Montipora
• Tyree Sunset Montipora
• Tyree Season's Greetings Monitopora

• Bali Tri-color Acro
• Garf Bonsai
• Blue Tort
• Acropora Millepora (10+ mini colonies)
• ATL Ultimate Stag

• Ultra Blue Tenuis
• Grape Ape Montipora
• Oregon Tort
• Vivid Efflo
• Steve Elias Stag
• $500 Efflo

LPS

• Cynaria
• Scolymia (6)
• Tyree War Coral
• Bumblebee Favia
• Tyree Baby's Breath Favia
• Cosmic Swirl Favia
• Vivid Prism Favia
• Chalices (80+) - All in frag tank - WAY too many to name! I have a slight chalice addiction!

I want to thank a few people that have helped me immensely in this hobby. First, thanks to Advanced Aquarist for the opportunity to feature my tank here. A BIG thanks to Andrew Harrow - this tank would never be up and running without your help! Thanks to my extended family and friends at www.Reef2Reef.com (where I'm proud to spend a LOT of my time). Sonny Harajly (SunnyX @ www.ProCorals.com) and Derek (Miracles in Glass) both helped a great deal with my tank decision. And thanks to Joe and Jan Genero (Fish World - Richmond, VA). If you're ever in Richmond please stop by and have a look at their shop. They are both a wealth of knowledge in this crazy hobby of ours. I'm very fortunate to have a LFS of that caliber in my neighborhood. That's it! I'm excited to see the reef grow in over the next few years. I'm confident there will be some changes...lol! And I certainly hope that my tank can live up to some of the other featured tanks I've read about here.

Feel free to visit my ongoing build thread at Reef2Reef - http://www.reef2reef.com/forums/large-aquariums-180g/51736-bagbos-dream-miracles-build-powered-sfiligoi.html#post563250

I suppose most serious hobbyists will watch a program concerning corals reefs on the Discovery Channel or Animal Planet (or other) television channels. With the cost of big-screen televisions rapidly falling in price and their use becoming commonplace, viewing these video essays on a giant screen can be spectacular. If you're a coral afficianado such as me, you'll especially enjoy those shows dealing with the invertebrates of coral reefs. Some of the most astounding videos can be of coral spawning. We the extreme close-up video of corals extruding their egg bundles to the shallow seas during early evening. It would be easy to believe that all corals reproduce in this manner but such is not the case. One such case is the coral Porites lutea in Hawaii.

Facts about Porites lutea (Milne-Edwards and Haime, 1860):

Phylum: Cnidaria
Class: Anthozoa
Subclass: Hexacorallia
Order: Scleractinia
Suborder: Fungiina
Family: Poritidae
Genus: Porites
Species: lutea

Figure 1. A field of purple Mound Corals (Porites lutea) in Kahalu'u Bay, Hawai'i. Note the tiny black 'Humbug' damselfish (Dascyllus sp.) bravely defending its home, the Pocillopora meandrina at the bottom center of the photo (by the author).

Porites lutea (formerly P. evermanni) is a common coral in Hawai'i and throughout the Indo-Pacific Ocean. These animals are mostly often found in water up to 6 meters (20 feet) in depth. Coloration can be brown, yellow-brown, gray, sometimes with purple highlights and less often entirely purple. It is never yellow-green like P. lobata (Fenner, 2005). Porites colonies are among the longest living animals known where some are hundreds of years of age.

Kahalu'u Beach Park on the west coast of the Big Island of Hawai'i provides a perfect spot to easily observe P. lutea and other coral colonies. A mysterious rock wall (Hawaiian legend suggests the wall was built by the Menehunes - a race of secretive, tiny people) shelters the bay from intense wave action and provides calmer waters preferred by P. lutea and a rapidly aging coral observer (me). Hence Kahalu'u is also a favorite spot to document coral spawning activities. Members of the ReefWatchers group have observed spawnings of Pocillopora meandrina, P. eydouxi, and Leptoseris bewickensis there.

The Department of Land and Natural Resources (DLNR) Division of Aquatic Resources monitoring team members provided some details of P. lutea's reproductive behavior (Sara Peck, personal communication). Evidence of a spawning was observed on July 9^th, 2009, sometime between noon and 1400 hours, while DLNR's Dr. Bill Walsh and Brent Camen were monitoring a transect line off the west coast of the Big Island Of Hawai'i. They observed a large cinnamon colored cloud of spawn surrounding and obscuring a P. lutea colony estimated to be some 9 meters (30 feet) across.

Would these corals spawn again the next day? Intrigued, I cancelled the plans I had and prepared to photographically document the daytime spawning of this species.

I had hoped to be in the water at noon on July 10^th, but as luck would have it, I would not get wet until about 1230 hours. The day was one straight out of a travel brochure - a blue sky above the palm trees, plenty of sun, and calm warm water. Snorkeling across the reef flat to the coral bommies, I noticed the water seemed a bit turbid, and within five minutes of entering the water I would know why. There was a mass spawning event of P. lutea occurring. The first colony (out of 7) I observed was apparently finishing its spawning, as I saw only one slow discharge of sperm. I hurriedly and clumsily opened my dive bag to remove a kitchen baster and a small plastic bottle and collected a spawn sample. I began to look for further evidence of spawning, and didn't have to go far - I entered a shallow depression filled with P. lutea - and they were all spawning (this almost mono-specific stand of Porites is in the introductory photo which was taken after the spawning event was over). Things were getting hectic. I had the baster and bottle in one hand, and the underwater camera in the other. Get a photo - take a sample. I needed some help. I surfaced and hailed a nearby snorkeler. I rapidly told him of the situation, and asked if he would help me. He nodded his head, and I began to take more photos and samples. I never saw that snorkeler again and can only suppose that swimming in a sea full of coral gametes held absolutely no appeal to him.

The best show was still to come. Even through the water's reduced visibility (estimated to have dropped to only 6 meters, or ~20 feet from a normal 16 meters - ~50 feet), I could see the outline of a massive P. lutea surrounded by an underwater fog of gametes (see Figure 2). I watched in awe as this coral slowly released gametes for at least 20 minutes (some colonies were observed spawning for as much as 30 minutes). More photos and samples were taken. After an hour, the spawnings stopped, but I stayed in the water for another 30 minutes in hopes of seeing female colonies releasing eggs (quick looks at my bottle with composited spawning samples had revealed no eggs during this very hectic hour). I reluctantly left the water as the bay's normal clarity returned, suggesting the event was over.

Once in the lab, I made my notes and a microscopic exam of the spawn sample. Unfortunately, I could not spot any eggs either visually or microscopically, and after examining quite a few detritus particles, I abandoned my search.

Figure 2. Spawning of a male P. lutea. Note the corona of cloudiness to the right and above the colony - these are release of sperm. Photo by the author.

Combining two observations, this is what we know about daytime spawnings of Porites lutea.

Spawning Event of July 9, 2009 (Observers: Walsh and DLNR monitoring team)

• Though not directly observed, a large female colony at a depth of 10 meters (30 feet) was obscured by a cloud of gametes (eggs).
• The cloud of eggs was cinnamon in color*, and 'sticky', clinging to wetsuits.
• Spawning occurred between noon and 1400 hours.

* Interestingly, at least some P. lutea eggs are known to contain zooxanthellae when released during spawning (symbionts are obtained from the parent colony through a process known as vertical transmission). This might account for the reported brownish coloration. However, see comments on the possibility of P. lutea being a gonochoric brooder below.

Spawning Event of July 10, 2009 (Observer: Riddle)

• Spawnings of 7 colonies were observed
• Colonies were apparently all males
• Slow continuous release of sperm appearing as 'white smoke' and lasting up to 30 minutes
• Entire spawning lasted at least one hour (12:35 - 13:35 hours)
• These spawnings occurred 2 and 3 days after full moon and on a rising tide (approximately 2.25 and 1.5 hours after the morning low tide, 7/9/09 and 7/10/09, respectively).
• Sexuality: Gonochoric (separate male and female colonies)
• Reproductive Mode: Broadcast spawner (sperm)*; no egg release observed
• Sexual Maturity Size: Smallest spawning colony was 450 cm² (roughly 72 square inches - 6x12 inches), but maturity could quite possibly be even smaller.
• No eggs were collected; however previous reports state eggs contain zooxanthellae (Neves, 1998).

* Parthenogenesis and brooding have also been reported as a possible reproductive mode in P. lutea (Fadallah, 1983).

Figure 3. An initial report of timing of P. lutea spawnings in waters of the Big Island of Hawai'i. Note that other researchers have noted P. lutea spawnings later in the year in Hawai'i.

Our observations are at odds with that reported by Kenyon (1995). Histological examinations of 3 P. lutea specimens gathered in May in Palau (7N, 138E) found no eggs.

Does P. lutea spawn earlier (or later) than those in Hawai'i, or is this a case of mistaken identity? Which leads us to our next topic.

Taxonomy

Corals are generally difficult to identify to the species level, and the specimens of genus Porites are particularly so. Porites lutea in Hawai'i were formerly called P. evermanni (thought to be endemic to Hawai'i). However, Forsman et al. (2009) report samples of Hawaiian P. evermanni are genetically indistinguishable and similar in corallite characteristics from a Panamanian Porites. In addition, it was identical genetically to a branching morph of P. annae from American Samoa.

Plasticity of coral skeletons due to any number of pressures creates the 'coral species problem' that will likely take some time to resolve.

We used the identification of P. lutea suggested by Fenner (2005), where gross morphology of the skeleton is used, as well as color. His observations and recommendations allowed us to successfully locate spawning Porites colonies within Kahalu'u Bay. A later conversation with Dr. Paul Jokiel validated Fenner's identification methods.

We should note that the Porites species closely resembling P. lutea is P. lobata. Information available to us states that Hawaiian P. lobata spawns during July and August evenings, two to four nights after the full moon and at 2100-2300 hours, or 0100-0300 hours (Gulko, 1995).

In Closing

To our knowledge, this is the first report of P. lutea's daytime spawning as early as July in Hawaiian waters. There is a report of Hawaiian P. evermanni reproducing in August and September just after the full moon (Hunter and Hodgson, unpublished, in Neves, 1998; also in Richmond and Hunter, 1990). Richmond and Hunter (1990) reported

P. lutea spawns during November and January (summer) on Australia's Great Barrier Reef. Obviously, our initial report is preliminary and will be refined with time.

The take home message is clear - not all corals spawn at night or do our observations of P. lutea's spawning behaviors correspond to any particular lunar phase. In fact, our observations suggest spawnings are random during periods of warmer water.

There is yet another possibility - some Porites lutea populations could use gonochoric brooding as a reproductive strategy, where sperm is released to the water column and fertilizes females' internally held eggs. This is rare in corals (estimated to be used by 7% of coral species) but has been reported in Porites rus colonies in Zanzibar (Bronstein and Loya, 2011). Hence, Porites species have been reported to use many reproductive modes - parthenogenesis, gonochoric broadcast spawning and gonochoric brooding (in addition to fragmentation).

Footnote

No observations, mostly due to time constraints of volunteers) of P. lutea spawning were made in 2010 (although they surely occurred). Our hopes are high for the 2011 spawning season, and we hope to have new information to report later this year.

References

1. Bronstein, O. and Y. Loya, 2011. Daytime spawning of Porites rus on the coral reefs of Chumbe island in Zanzibar, Western Indian Ocean (WIO). Coral Reefs, in press.
2. Fadallah, Y., 1983. Sexual reproduction, development and larval biology in Scleractinian corals: A review. Coral Reefs, 2: 129-150.
3. Fenner, D., 2005. Corals of Hawai'i. A Field Guide to the Hard, Black, and Soft Corals of Hawai'i and the Northwest Hawaiian Islands, Including Midway. Mutual Publishing, Honolulu. 144 pp.
4. Gulko, D., 1995. Hawaiian Coral Reef Ecology. Mutual Publishing, Honolulu. 245 pp.
5. Forsman, Z., D. Barshis, C. Hunter and R. Toonen, 2009. Shape-shifting corals: Molecular markers show morphology is evolutionarily plastic in Porites. BMC Evol. Biol., 9:45.
6. Kenyon, J., 1995. Latitudinal differences between Palau and Yap in coral reproductive synchrony. Pac. Sci., 49(2): 156-164.
7. Neves, E., 1998. Reproduction in reef corals. Results of the 1997 Edwin W. Pauley summer program in marine biology. University of Hawai'i, Hawai'i Institue of Marine Biology. Technical Report No. 42.
8. Richmond, R. and C. Hunter, 1990. Reproduction and recruitment of corals: Comparisons among the Caribbean, the tropical Pacific, and the Red Sea. Mar. Ecol. Prog. Ser., 60: 185-203.
9. Thongtham, N., Transplantation of Porites lutea to rehabilitate degraded coral reef at Maiton Island, Phuket, Thailand. Proc. 11^th Int. Coral Reef Symposium.
10. Veron, J.E.N., 2000. Corals of the World. Australian Institute of Marine Science.

The Family Pomacentridae contains over 300 species altogether, some of which are without a doubt the most common fishes in the marine aquarium hobby. Almost all of them are marine, primarily being found in the Indian and Pacific Oceans, but there are a few that may be found in brackish waters, and several species are found in the Caribbean Sea and Atlantic Ocean, as well.

Some of these species are as colorful as a fish can be, and many stay relatively small in size. Some can get along just fine with other fishes and invertebrates, and they're relatively inexpensive, too. So, they sound wonderful as a whole, but the problem is that only a few species make good additions to most aquariums, rather than all of them. The fact is, despite the general popularity of these fishes, many can be absolutely nasty towards their tankmates. Some get much, much bigger than you might think, and some get quite plain looking or even ugly as they age, too. So, this clan of fishes certainly merits a closer look.

Most of the members of the family are simply called damsels by hobbyists, but some members are called chromises, all of which belong to the genus Chromis. The clownfishes, which hang around in anemones and belong to the genus Amphiprion or Premnas, are also in the same family with the rest of these, too. But, we'll be sticking with just the "regular" damsels and the chromises here. Clownfishes, despite being in the same family, are unique enough to warrant full-coverage in their own article.

The Good

There are many good things to say about the damsels and chromises. Many are very colorful, and some actually seem to glow under bluish-colored aquarium lighting. Even those that are covered only by black and white stripes and spots can be attractive, as well. Again, many also stay relatively small, even when full grown, which is desirable to most reefkeepers. In fact, quite a few of them won't get any larger than two or three inches at the most. I've provided the maximum reported sizes for several species below (from www.fishbase.org), but keep in mind that these are exactly that - maximums. Most specimens won't get so large in aquariums, and are often considerably shorter in length even when perfectly healthy and well cared for.

Some species will get along well with other individuals of the same species, and with other species of fishes, too. Many can even be kept in groups of several individuals, which will move around larger tanks in schools. And, almost all of them will leave whatever sorts of non-fish life you have alone, as well.

Additionally, the damsels (but not so much the chromises) are categorically tough. Very hardy indeed, so much so that they have been the number one type of fish used to cycle new aquariums for as long as they've been available as best as I can tell. Less than stellar water quality is seldom a problem for them, and most will survive the process of establishing the biological filtration cycle in a tank in stride. No they aren't bulletproof, but compared to other sorts of fishes, they're certainly ranked high when it comes to survivability under adverse conditions.

As best as I can tell, they'll also eat just about anything that you add to a tank that is considered fish food. Flake food, brine shrimp, blood worms, fine bits of fish, clam, and squid meat, sheets of algae, frozen cube foods, etc. Most of them will take it all, and will nibble at some of the unwanted algae that grows on rocks and such, too.

And, as if that's not enough, they're cheap. Marine fishes are quite expensive compared to freshwater fishes, but damsels and chromises can still be picked up for just a few dollars at any shop you might visit. Thus, there are lots of reasons to like them.

The Bad

As great as all of that might sound, there are some problems when it comes to many of the damsels. In fact, many of the commonly offered species should be avoided by reef aquarists altogether. Keep in mind that doesn't mean these same undesirable species aren't perfectly fine by themselves in a nano reef, or in non-reef aquariums stocked with larger/more aggressive fishes that can take care of themselves, though.

Regardless, some damsels may be very colorful when they're small, but lose their desirable appearance as they age. Some actually turn completely brown or black when they are mature. Some of them can get much bigger than you might think, too. Several species that are often seen at shops at one to two inches in length can grow and grow until they're the biggest fish in a tank at times (depending on what else is in the tank, of course).

Still, these are trivial issues compared to the absolutely nasty attitudes many damsels have. Even at small sizes, these fishes are often territorial in nature, and can decide that a large section of a large tank is their territory, or that everything within a small tank is. They'll defend what they consider to be their own real estate, even against peaceful fishes that are much larger than they are, to the point of pestering them to death. Such damsels will chase and nip at practically any fish that doesn't have the guts to fight back, and you'd be surprised at how many larger fishes won't. If this persists, the victim will oftentimes become highly stressed since there's nowhere to move on to, so that they'll hide all the time, and may end up sick, and might even die. Large damsels may outright murder smaller fishes, too.

Speaking of, in general you should never try to keep more than one damsel of the same species together unless they have plenty of room and hiding spaces. For that matter, it's usually a bad idea to mix different species in confined quarters, too. Remember, they can be very territorial, and another damsel, regardless of type will typically be seen as a direct competitor for space. However, some can be kept in schools at times, and the same goes for the chromises. In fact, the popular chromises are best kept in groups and will stick together and swim around in a pack, oftentimes near the top of a tank.

I'll also add that while they typically won't bother invertebrates, there are some species that will snack on tiny worms and crustaceans that are quite beneficial in some tanks, especially those that have deep sand beds. Little things like amphipods and copepods will make quick meals for some of them. All things to be considered...

Some Common Species

There are lots of damsels and chromises, but I've listed a few common ones below, all of which I've had some personal experience with as a hobbyist and when operating an aquarium maintenance business in the past. Just enough to give you a good idea of the variability found between the species, and what may or may not be a good choice for your aquarium. Keep in mind that how common a species is at shops, or how popular they are overall, has little or nothing to do with how suitable they are for a reef aquarium. As you'll see, many of these are no good for reefers, even in large aquariums.

The sergeant major damsel, Abudefduf vaigiensis

The sergeant major damsel.

Named for its sergeant-striped body, these damsels and their close cousins can be spotted on just about any dive, anywhere there's warm water. This is one of the species that looks cute when small, but can grow to a whopping 8 inches and may eat small invertebrates if given the chance.

The blue devil damsel, Chrysiptera cyanea

The blue devil damsel.

Awesome blue, but called a devil and a lot of other words that I can't write here for good reason. They only reach about 3 inches at best, but when it comes to nastiness, these little things can be real terrors. I've added these to reef aquariums in the past, and regretted it on every occasion. So, they're off-limits now, no matter how cheap, tough, and pretty they are.

The yellow tail damsel, Chrysiptera parasema

The yellow tail damsel.

Mostly blue with a bright yellow tail, these are a little smaller than the blue devils and are far less aggressive. That doesn't mean they're necessarily peaceful though, and for a fish with a maximum size of about 2.5 inches, some individuals can be surprisingly obnoxious. Still, these are a far better choice than a blue devil, and most times they don't cause any troubles, so I generally recommend them.

The azure damsel, Chrysiptera hemicyanea

The azure damsel.

This species also reaches about 2.5 inches, and looks a lot like a yellow tail with some extra yellow. The tail and the whole belly is bright yellow, with the rest being that same blue color as the two previous species. These are some of my personal favorites, as they tend to be even less aggressive than the yellow tails, although I have had a couple over the years that had poor attitudes. Still, I like them enough to recommend them, too.

The talboti or Talbot's damsel, Chrysiptera talboti

The talboti or Talbot's damsel.

This one also reaches about 2.5 inches, but doesn't look at all like the three above. No blue body on this one, but they still have attractive colors, with a black spot on their back. Very pretty, and quite possibly the most peaceful of all the damsels. This species is highly recommended due to its generally peaceful nature, small size, and hardiness, as well.

The three-stripe damsel, Dascyllus aruanus

The three-stripe damsel.

It is odd to me that with all the colorful marine fishes out there, some that are only black and white are still neat looking enough to bring home. The three-stripe is a good example, as its look is nothing more than 3 broad black and white stripes on a body that doesn't get more than about 2.5 inches long. Unfortunately, they not only lack color, but they generally lack any tolerance for other fishes, too. Yes, they can be pretty mean.

The four-stripe damsel, Dascyllus melanurus

The four-stripe damsel.

This one is very similar to the three-stripe damsel in both appearance and attitude. They get just a little bigger, maybe reaching about 3 inches, and they have a black tail rather than a white/clear one, but that's about it. Mean again.

The domino or three-spot damsel, Dascyllus trimaculatus

The domino or three-spot damsel.

These will fool you for sure. They're seen for sale everywhere and look like cute little dominos when young, but they can also be very aggressive, too. What's worse is that they typically lose the bright spots, turn a kind of crummy black, and get up to 4 inches long.

The neon-velvet damsel, Neoglyphidodon oxyodon

The neon-velvet damsel.

Same for this one, but worse. When young, this species has cool looking neon blue racing stripes on its black body, but they lose these and turn completely black as they age, and can get up to about 6 inches in length. These are also exceptionally aggressive, even more so than the domino damsel, and I say should never be added to a reef tank.

The Atlantic jewel damsel, Microspathodoon chrysurus

The Atlantic jewel damsel.

Same, again, except that these will loose all of their bright spots and grow to about 8 inches in length. Mean, mean, mean. Big ones will even take a nip at divers that get too close, which I've experienced myself.

The blue-green chromis, Chromis viridis

The blue-green chromis.

Finally, we get to something else that I can recommend. The blue-green chromis is a nice color, only gets up to about 3 inches maximum, can be kept in groups, and won't bother each other or any other sorts of fishes either. Nice. On top of that, they also like to hang around near the top of aquariums, rather than constantly hovering close to and moving about the rockwork. This species is great for larger/deeper tanks, as a small school of them can really add to the overall look, instead of having a lot of less-traveled or even empty space at the top.

The blue chromis, Chromis cyanea

The blue chromis.

Another schooler, which can be kept singly if you like, these can also be kept in groups and are generally peaceful. This species can reach a maximum of about 6 inches in length though, so they may get a little bigger than what you want. Still, if you don't mind the size, these are a much better choice than the blue devil damsel if you're looking for something blue.

To End

So, that's enough to give you a pretty good idea of what these fishes are like, and as I'm sure you noticed, I only recommended a handful out of these species for reef aquariums. Of course, there are so many species that I can't cover even a significant percentage of them here, but you've got the basic idea now. Thus, it's up to you to do some homework if you want to try any of these or the others, and I suggest taking a look at Fish Base (www.fishbase.org) before making any purchases. On this site you'll able to find some specific information about their maximum sizes, habitat, and diets, etc. to help you make informed decisions, and you can often find juvenile and adult photographs for many of them, as well.

Sanjay discusses the design points he considered when converting his 180 gallon coral reef display to a spectacular 500-gallon reef tank. He shares details relating to the design, set-up, and maintenance of this tank, offering the home aquarist both inspiration and invaluable reef-keeping advice. As always, just send any questions to AmericanReef@me.com or sound off in the comments below.

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