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You are here: Home Volume VI July 2007 Aquarium Fish: Triggerfish

Aquarium Fish: Triggerfish

By Jim McDavid Posted Jul 14, 2007 08:00 PM Pomacanthus Publications, Inc.
Triggerfish are highly resilient animals, and for the most part they ship well and feed from the time they are collected to the time they make it into your home aquarium.

Many aquarists, both freshwater and marine alike, first become interested in this hobby by simply deciding one day, for one reason or another (maybe after seeing a friend’s tank) that they would like a fish tank in their living room. Then, (hopefully) some research begins, and at some point during the many trips to the fish store and hours spent reading every article and book available, the new hobbyist decides on what fish he wishes to populate his newly set up tank with. A particular favorite or two may emerge, and if the aquarist is lucky, these are hardy, compatible, easily obtained species.

Others like myself, were seduced into the hobby by a single particular fish, and all thoughts and actions surrounding and leading to obtaining that magical glass box centered on the needs of this one fish. Obsession follows, and all the research and purchases are made to accommodate this must have animal. The origin of my involvement in the marine fish hobby over two decades ago falls into the latter category. The fish, or rather group of fish that so irreversibly pulled me in were the members of the family Balistidae – more commonly known as the Trigger fishes. In the years since, I’ve expanded my interests and have kept representatives of just about any family you can name, but if I could keep only a single fish in a single tank, it would undoubtedly be a Triggerfish.

What exactly is a Triggerfish?

Not your average aquarium denizen for sure. Let’s take a look at what makes them so unique.

Triggers belong to the order Tetradontiformes “four-tooth bearing”, and the family Balistidae, and are closely related to 9 other families, including among others, cowfishes, filefishes, puffers and leatherjackets. Most species in the order, and certainly all the members of the family balistidae practice balistiform locomotion (using the dorsal and anal fin rather than the caudal fin) almost exclusively, although the caudal fin is sometimes used for short bursts of speed. In simple terms, these fish do not normally use their tail for swimming, but instead undulate their dorsal and anal fins, keeping the body rigid. This gives the effect of a small hovercraft moving about, and is part of what endears the fish to so many hobbyists.

The Balistoids are laterally compressed, generally rhomboid shaped fishes, although a few species are slightly elongated. They have a non-protrusible upper jaw, with hard, specialized teeth that in most species are designed for cracking the shells of various hard-shelled invertebrates. They have independently rotating eyes, and their pelvic fins are fused into a single spine. They have two dorsal fins, the first of which is comprised of three spines, and this is where the Triggerfish derives its name. They can use this spine, along with the ventral spine to lock themselves into coral heads or rock crevices when threatened, and once they do, they are immovable!

From an evolutionary standpoint, triggerfish are some of the most advanced fish in the sea. They are heavily armored, intelligent hunter-killers of the reef, and have a set of jaws that can annihilate any hard-shelled invertebrate you care to name They can also destroy just about anything else you care to name, both alive and otherwise, but we’ll get to that shortly.

Interesting, but why would I want one?

For starters, as with other members of the order, Triggers are atypical to say the least in the morphology department. A vast majority of fishes seen by both freshwater and marine hobbyists belong to the order Perciformes, or “perch like” to use the common term. While we can get technical again, it will suffice to say that all these fish share certain morphological characteristics that cause them on the whole to look more the same than they do different. You may have a Clownfish, Angelfish, a Surgeonfish and a Dottyback residing in your tank, and while they are seemingly quite dissimilar, they’re really quite close in morphology and are for the most part variations on a theme. Fish of the order Tetradontiformes however are strikingly different than their cousins in the order Perciformes, there is just nothing else in the ocean like them. They almost give an impression of some sort of alien craft maneuvering here and there rather than fish. .In this assemblage of very unusual and interesting fishes, the Triggers are the most suitable for aquarium life for a variety of reasons. While some notable exceptions exist, the equally stunning, intelligent and bizarre fishes belonging to the other families in the order are often either very delicate, notoriously disease prone, (internal and external parasites) poor feeders in captivity, or exude toxins that can wipe out an entire tank. Some will even provide you with a combination of these traits! Fortunately, the Triggerfish share none of the above problems with their other relatives in the order.

Aside from their unique morphology, the next thing that will grab your attention about a Triggerfish is the color. A few species are like living, breathing modern art paintings, and the Picasso Triggerfish in particular looks like something out of a children’s story, almost too fanciful to be real…but there it is! A few species are just out and out garish, while some have a more subtle beauty.


Picasso Triggerfish

One of the other striking qualities about the family as a whole is the obvious intelligence exhibited by these fish. Triggers are very deliberate in the way they go about their business, and don’t move about in a seemingly mindless or programmed fashion exhibited by some other genera. You can almost see the gears turning as they examine their surroundings, or maybe contemplate a possible food item or a newly introduced object or inhabitant in their environment - eyes rotating like some advanced sensor al the while. As with freshwater fish of the family cichidae, they can learn to recognize their keepers, and further, what behavior by their human keeper usually results in a treat being introduced into their home.

Are you convinced yet? How about this - they are hardy…no, indestructible! Well, that might be overstating things a bit, but let’s just say that if you can’t maintain a Triggerfish in a healthy, thriving state, you best turn in your glass box and go get a pet rock, because that’s about the only thing tougher than one of these fish. They are as forgiving as aquarium fish get, and not even amongst their commonly kept freshwater relatives can you find a more resilient fish. Among other things, this of course means that they are tremendously disease resistant. This quality alone should automatically endear them to most potential owners immediately. They rarely succumb to the common marine parasites that rear their head now and then in captive systems, and in over 20 years of keeping marine fish, (including the early days when my husbandry practices were not so careful as they are now) this author has never lost a Triggerfish to any marine fish disease. On the rare occasion that a Triggerfish does become infected with a parasite such as Cryptocaryonirritans (saltwater ick) they recover with just a bit of TLC on the part or the aquarist. If that doesn’t convince you, back in the day when cycling a new tank with live fish was the norm, I used Triggers of the genus Rhinecanthus on more than one occasion instead of the more normal damsel fish for this task. I’m not advocating this practice of course, this was many years ago, and we’ve moved away from even using Damsels to cycle new tanks. It should nevertheless be a fairly good indication of the inherent hardiness of the family as a whole. Having said this, there are Trigger species that while still hardy by most standards, would not fare so well under such treatment.

What else do I need to know?

Plenty! Let’s begin with choosing a suitable tank: The tank you will need to house your Triggerfish depends on the species you plan to keep, and what you plan on keeping it with. Some Triggers always end up alone, or traded back to the fish store, regardless of the extent to which they tolerate tank mates when young, so the aspiring trigger keeper needs to keep this in mind when selecting the species to be kept. Others will live out their lives in a community setting with few problems provided enough space is provided, some stocking order rules are honored, and tank mates are chosen with some care. A few will even live in a reef setting. In any case, tall narrow tanks should be avoided, as these are very active animals, and need as much swimming space as can be provided. A hexagonal tank is a very poor choice for a trigger unless it happens to be a very large one.


Undulated Triggerfish (Balistapus undulatus)

As is the case with many families, a wide gamut of adult sizes, growth rates and temperaments makes generalizations difficult with regard to the minimum tank size. Further complicating the matter is the fact that even though a given species may attain say 14” in the wild, this doesn’t necessarily mean that such a size is realistic in captivity, even when kept in the largest home aquaria. Others are just tremendously slow growers, and are not likely to reach anything close to adult size even after 6 or 7 years of captive life. A good example of this is the genus Rhinecanthus, which comprises a few very popular species, including the Huma Huma Trigger (R. aculeatus) and the Rectangular Triggerfish (R. rectangulus). While fish of this genus are without a doubt some of the most easily kept and sociable of all trigger species, they are also very slow growers - annoyingly slow if truth be known. If you want a nice adult show specimen, you have a true exercise in patience ahead of you unless you purchase an individual that’s already in the 7 or 8” range. For this reason, a young specimen, say in the 2” range can be purchased and comfortably housed alone in a 40-gallon tank for at least 12 to 18 months before larger quarters are needed. Long term, 70 gallons will generally do since once they reach 5” or so, their growth slows down even more. The above can also be applied to the Undulatus Trigger (Balistapus undulates). The primary difference here is that an Undulatus MUST be kept alone, for they are without a doubt the most aggressive aquarium species available, either freshwater or marine!

A few commonly seen species get quite large, and grow at a much faster rate than our beloved Rhinecanthus species. Among these are the Niger Trigger (Odonus niger), the Queen Trigger (Balistes vetula), the Clown Trigger (Balistoides conspicillim) and the Blue Line Trigger (Psuedobalistes fuscus) All four are relatively fast growers and require very large tanks as adults. We’re talking 500 gallons plus for the Queen, and at least a 200-gallon tank for the remaining 3 species. Of the four, only O.niger generally makes a good tank mate over the long term when kept with other fish, while the enormous size and aggression displayed by the Queen Triggers makes long term cohabitation with other fish all but impossible. The Clown Trigger and Blue Line fall while quite aggressive, are still a bit more social that the Queen, and if acquired small can live quite comfortably in a 55 or 70 gallon tank for some time before a larger tank becomes necessary, and they will even coexist with other species for a time if enough space is provided. This almost always changes at some point though, so be warned! The Queen grows much too quickly to consider anything but a very large tank from the get go Having said all this, a tank of at least 70 to 80 gallons will provide sufficient space on a long term basis for the vast majority of Triggers that you’re likely to encounter at your local fish store if kept alone. Even with the more sociable species, you will be very limited as far as suitable companions unless even more space is afforded.


As mentioned above, Triggerfish are highly resilient animals, and for the most part they ship well and feed from the time they are collected to the time they make it into your home aquarium. Unlike members of some other genera, adult Triggerfish generally ship well and thrive in captivity, as to quite young specimens above the 1.25” mark. However in this hobby, as with all things, nothing is all the time, and Triggers can and do become sick deteriorate if not cared for properly after collection. When looking for a suitable animal, make sure that it’s robust, with no concave or sunken regions on its flanks. One of the most common problems is emaciation due to lack of proper nourishment, and a fish that’s not of proper weight should be avoided. The prospective keeper should also watch for cloudy areas or spots on the eyes, fins and body, as well as poor color. Very small specimens can sometimes be difficult, and some species are more prone to problems here than others. One the worst in this regard is the Clown Trigger, and very small specimens under an inch in length often last only a matter of weeks in captivity. Still, bear in mind that the Trigger should be the smallest fish in the tank (for those species where cohabitation is a reasonable option) and specimens in the 1.5”range and larger usually make an excellent choice. Of course, the Trigger must be of sufficient size to prevent it from being consumed by larger piscivores that might already be present in the system.


As mentioned above, certain species of Triggerfish are more appropriate than others for long-term cohabitation with other fish species. Some are just too large and/or aggressive to expect them to live successfully a community setting for more than a short time. While these species can certainly be kept with other species when small, attempting to keep them in a community setting once they begin to put on some size usually ends in tears – these are very powerful, and potentially very destructive fish. The advice given here is meant to provide the keeper with a long term husbandry solution.

Fortunately there are species that usually do quite well when mixed with other tough marine species in large quarters. Among the most commonly seen species that fit this description are those of the Rhinecanthus genus, which includes R. aculeatus, R. assasi and R. rectangulus. More than one Triggerfish from this genus can even be kept in the same tank, but they should be introduced at the same time to avoid serious territorial aggression. Also, despite it being a larger species, Odonus niger does quite well in a mixed species setting provided the tank is large enough to accommodate it’s considerable adult size, in the 20” range. Unlike some species, this one will grow to full adult size in reasonable time if cared for properly.

The Halfmoom and Bursa Triggers, (Sufflamen chrysopterus), and (Sufflamen Bursa) respectively can also be kept in a community setting, as can the Pinktail Triggerfish, (Melichthys vidua), the Bluechin Triggerfish, (Xanthichthys auromarginatus), the Crosshatch Triggerfish, (Xanthichthys mento), and the Sargassum Triggerfish, (Xanthichthys ringens). The latter 4 species, as well as Odonus niger have the distinction of being generally safe in reef settings, with the caveat that small shrimp should be added before the Triggerfish, and the Triggers themselves should generally be added last, and be the smallest fish in the tank. In fact, in all cases your Trigger should be the last and smallest fish added to the community. The reason for this is that even relatively peaceable species like the Huma Huma, are only peaceable in relative terms! They are still somewhat aggressive fish, and can do a fair amount of damage in an altercation. For this reason they generally should not only be added last, but also be the smallest fish in the tank. This mitigates the damage that these fish are capable of, and allows the Trigger to become conditioned to the presence of his/her tank mates. Simply following these two rules generally assures that the Trigger does not establish itself as the dominant fish in the community, and allows the other inhabitants to adapt to the presence of the Triggerfish. For their part, Triggers are not generally susceptible to stress from larger, bullying tank mates, and they are quite well armored against anything short of a depth charge attack!

Ok then, what the heck can I keep with it?

Fortunately you have many choices in this department, and if we’re talking about O. niger, M vidua, or one of the Xanthichthys species, your choices are almost unlimited. These species can be kept in reef setups, and often to even bother small shrimp if the shrimp are introduced before the Trigger. For the purposes of this section though we’ll assume that we’re talking about a Rhenicanthus species, a Sufflamen species or ‘gulp’ a young Clown or maybe a Blueline Trigger. Remember, you can keep them in a community for a while, and the fact that many people do is the reason why I mention them here. Unfortunately, this practice is normally the result of ignorance rather than the knowledge that sooner or later other living arrangements will have to be made. I include them here because I know that no matter what I say here, people will do it. Just remember, soon or later something will have to give! I can’t in good conscious include the Undulates even with a disclaimer. This author witnessed a 2” Undulatus attack a 15” Queensland grouper seconds after being introduced into a 200 gallon aquarium.(We won’t get into how appropriate it was to be keeping a grouper that attains a length of ‘cough’over 8’) The Trigger barely had time to take a breath before it was biting the much larger fish…relentlessly I might add. Total elapsed time for the “maybe I’ll get lucky and it will work for me Undulatus cohabitation experiment” – 90 seconds. This small chunk of empirical data, coupled with testimonials from numerous other aquarists leaves me no qualms about stating that this fish should not be kept together with other non-food item fish…ever. A few anomalous occasions where people can get away with it for a short time (it’s happened) shouldn’t persuade you to try it – be warned!

Having said all of this, as long as the aquarist follows a few rules and employs some common sense, tank mates are not hard to come by – there are actually plenty of choices.

Among the best tank mates are Hinds of the genus Cephalopholis, and for all the reasons why, you can simply see my recent article on these wonderful fish.

These fish are beautiful, hardy and intelligent, and contrary to common perception, not generally aggressive toward members of other families. They are however more than assertive and robust enough to hold their own in the presence of most Balistoids. True groupers of the genus Epinephelus make great tank mates as well, as long as you obtain one the few species that remain small enough to be kept in a large home aquarium Within this genus, a few of the better choices are E. ongus, E. hexagonatus, E.merra. One simply needs to make sure that the sizes and growth rates of the fish are taken into account so that the Trigger does end up being a late night snack for the Grouper or Hind in question.

The larger, hardier angel species do well with Triggerfish, as do many wrasse, surgeonfish, and damselfish species, as well as various moray eel species.

Lionfish are often falsely lumped into the “aggressive fish” category like the Hinds, yet unlike the Hinds I cannot recommend them as tank mates for most Triggerfish species Some of the more rambunctious Triggers may harass the Lionfish and even nip spines off. In fact, various degrees of physical trauma is a danger with any slow moving or relatively sedentary fish species kept with certain Triggers. Back when I was younger and working at a local fish store, I witnessed an adult Clown Trigger remove the eyes from a 2’ Cat Shark soon after being introduced into a 400-gallon aquarium. An unfortunate incident, and a reminder that the destructive potential of these fish should not be underestimated, and tank mates need to be chosen wisely.

Remember, careful tank mate selection which takes into account size, including initial relative size and growth rate, and stocking order are 3 things to that must be strongly considered when stocking your mixed species tank. Triggers almost without exception should be the final fish added.

What if I want to keep him alone?

Then you’re in for an extremely rewarding and entertaining experience, and only the size tank you can invest in limits your choice of Triggerfish. Keeping a single fish alone in a species tank is the only viable option for certain species, including B.undulatus, and V. vetula – the Undulated and Queen Triggers respectively. In fact, of the dream tanks that this author aspires to keep on day is a 120 gallon tank with a single, adult Undulates Trigger. For the B. Vetula, the 2’ Queen Triggerfish, it will have to be a tank in the 500 gallon range. Now the aquarist is only faced with the challenge of dealing with the highly destructive capabilities of these fishes, and nothing is safe! This means filters, powerheads, power cords and heaters! For this reason, these items are best kept in a sump, and out of the main tank. They are also adept, (and seemingly quite fond of), overturning and moving rocks and other pieces of décor. This tendency should be taken into account when aquascaping a tank that will eventually house and adult Triggerfish.

Speaking of things that should be kept out of the main tank, add your hands and arms to the list! As much as possible anyway, you should avoid inserting your hands into a tank containing a large Triggerfish – they can draw blood, and larger specimens (though unlikely to be found in your home tank) can remove fingers. The jaws of these fish are highly effective at what they are designed for, which is dismantling all manner of hardened items found in their environment. Always be aware of where your Triggerfish is when doing maintenance of your tank, even smaller specimens can deliver a painful and shocking bite.


The news couldn’t be better in this department – feeding a Triggerfish is the easiest thing you can imagine. Most species feed on hard shelled invertebrates in the wild, so they spend their day browsing the reef for crabs, shrimp, snails, etc. In captivity, they will accept a wide range of fresh and prepared fish foods, only leaving the aquarist the task of making sure that a variety of food items are offered, and that vitamin supplements are administered now and then to insure proper nutrition. Aside from a variety of appropriate foods that can be purchased in frozen form at most better fish stores, the aquarist can brows the seafood counter at his or her local grocer, and find many things that will have a Triggerfish eating out of the keepers hands in no time flat. A few of these items are fresh squid, octopus, scallops, fish, shrimp and crab. These foods can be cut into bite sized morsels and offered to the Trigger 2 or 3 times a day. Whole crayfish can even be offered, shell and all, and this will allow you to witness the business end of a Triggerfish doing what it was meant to do…demolish and consume! Even the few available species that are planktivores in the wild readily accept and thrive on all the options mentioned above with the exception of large, whole invertebrates.


Too big for all but the largest of aquariums, this Titan Triggerfish, (Balistoides viridescens), grazes in the company of several Undulated Triggerfish (Balistapus undulatus)

One thing bears repeating here, and that is the importance of vitamin supplements. The primary reason for this is that feeding a predatory animal of any kind (be it bird, reptile, or fish) meat only does NOT replicate it’s natural diet in full. The predator in question is a consumer of whole animal items. When a Trigger consumes a crab in the wild, it not only ingests the meat, but all the blood, organs and other matter other that makes up the animal - not simply meat. Feeding a combination of whole food items and vitamin supplements mitigates any problems that my rear their head down the road due to improper nutrition, including but not limited to, poor color.

In Conclusion

Within the vast array of species available to the marine aquarist, the Triggerfish are among the most interesting, unusual, and rewarding to keep - there certainly is no single fish that is more entertaining or more “pet” like. From the subtle beauty of Odonus niger, to the dazzling brilliance of Ballistoides conspicillim, there is something for every hobbyist within this family. As long as the aquarist takes potential problems into account, and chooses a species compatible with the available tank space and other desired tank mates, few problems should be encountered. Even those with a large reef have several choices within this spectacular family of fish. If you want something easily cared for, that eats like there’s no tomorrow, and has loads with of personality, consider one of these beauties.

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