Triggered!

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Sleek, colourful biting machines, the triggerfish are part of the old guard of marine tank inhabitants. Here’s a guide to some of the nicest species for a fish-only set-up.

In my time as an aquarist, in both the professional and the hobby sense, I’ve been bitten by a lot of things. I’ve felt the slice of sharks cleaving my hands, I’ve had my knuckles crunched by the crustacean-crushing teeth (actually modified scales) of rays, I’ve had the skin rasped from my wrist by furious Spotted tilapia, and I’ve had a Tiger barb swinging from a mole on my forearm.

But there’s a small cabal of aquarists, spread far across the globe, who know exactly what it’s like to be bitten by a triggerfish. I’m one of them, and I can testify that it is the most painful bite I’ve ever felt. My other bites have been accidental, or from curiosity at most. Triggerfish, by contrast, are more malicious, going back for repeated nips. And when a bite occurs it’s deep and damaging. Think of someone going at you with electrically charged nail clippers. It feels just like that. 

Bearing that in mind, why on Earth would anyone want to put these well-armed brutes into an aquarium? Often, they don’t, aside from the calmest and smallest species, and even then with extreme caution. Most of these fish are decidedly unsafe in the reef tank, and will prey upon any molluscs and bivalves, shrimps and crabs, as well as small and medium fish. I’ve seen them biting corals before, seemingly just for fun. 

Yet for some, the allure of belligerent fish is considerable, and kept alongside marine ‘tankbusters’ like lionfish, groupers and the heftiest of angelfish, (some) triggers can fit in just fine. In fact, I can’t recall a single occasion where a trigger has been bullied by another fish. 

Triggers are mostly mid-sized fish. Their adult sizes sit between 15 and 50cm, with one giant outlier, the Stone triggerfish, reaching over 100cm fully grown. The ‘trigger’ name comes from the unique anatomy of the dorsal fins — to avoid being eaten, they can lock their dorsal fin spines firmly into place (wedging themselves between rocks), and these can only be released again by the depression of another ‘trigger’ spine that holds them in place. 

Feeding is straightforward enough, with crustaceans and fish being the order of the day for most trigger species, while a few (chiefly the species of Melichthys) also require some algae in the diet. 

While most of what I’ve written might come across as pejorative, I don’t want to leave that impression. In the right tank, and with the right tankmates, many of these triggers will make astounding and lively feature fish. They rarely hide, they feed ravenously, and they develop a dog-like devotion to their owners. I wish I had a tank big enough for one of my own, frankly. 

Read the rest of the feature in the January 2022 issue. Buy the latest digital edition and read instantly on your computer, mobile or tablet device.


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