The peculiar warning sign of the triggerfish
When I was at an aquarium not so long ago, I came past an aquarium with a fish hiding all the way in the back by the rocks, hiding in the shadows of the cave. It looked almost black. As I came closer to the glass, it shot towards me, swimming with peculiarly shaped fins at the top and bottom of its body. This gave its way of swimming a charming sway. Although, I wouldn’t have used the word charming if I was in the water with this fish.
Many divers are probably familiar with the family of fish this species belongs to, triggerfish (Balistidae). These fish are quite aggressive and have teeth that can do some damage. Thus, divers like to avoid them. I don’t blame them.
My aquarium encounter was with the blue triggerfish (Pseudobalistes fuscus), who turned out not to be black at all. This one also wasn’t as blue as the name would suggest. The top part of his body was more reddish and the bottom part more yellowish. This colour scheme makes him appear black in the dark, excellent camouflage.
Teeth
The first thing that I find extraordinary about these fish are the teeth. Even though the majority of fish species have teeth, teeth still are not something I quickly notice when admiring fish in the aquarium or in documentaries. But these fish have very prominent teeth, which are also funnily shaped. And when the triggerfish shoots toward you, the teeth are definitely something you can’t keep your eyes off. That is with good reason. Plenty of divers have gotten nasty wounds from their bite.
Their teeth are hard and they have a strong bite. This is useful for their diet that consists of hard foods like shellfish, sea urchin, and coral. Thus if you get bitten it isn’t because they would like to have a little snack. You’re not part of their diet. It’s purely out of self-defense.
The trigger
The thing that really fascinates me about triggerfish is the “trigger”. Fishes from the Balistidae family have three spines at the top of their body. Usually these spines are retracted, but when a predator comes close these spines “pop up” and will stand erect on the top of their body. A reason for this erect spine to clamp themselves into crevices of rocks. When doing so a predator is unable to pull them out of there.
This trigger is also a good warning sign for divers. When those spines go up, you need to get the hell out of there.
Sources: https://www.fishbase.se/summary/FamilySummary.php?ID=445 https://en.wikipedia.org/wiki/Triggerfish https://www.inaturalist.org/taxa/49612-Balistidae https://redseacreatures.com/taxon/fishes/bony-fishes/triggerfishes
