The largest triggerfish on the reef at 75 cm (30 in): a heavy diamond-shaped body in olive and dark green, each scale outlined so the fish looks tiled, with a dark moustache line above the mouth and small high-set eyes it can swivel independently.
The teeth are the point. Eight heavy incisors in each jaw crush sea urchins, coral and thick-shelled molluscs, and the fish routinely picks up rocks and flips them to get at what is underneath. Smaller fish follow it around all day to take what the excavation exposes.
A nesting female will attack a diver, and knowing the shape of her territory is the difference between an incident and a non-event. The nest is a shallow crater in sand, and the territory she defends rises above it as a cone that widens toward the surface - so swimming upward keeps you inside it, and swimming up and away puts you further in, not further out. Get out sideways, staying low, keeping the fish in sight. Fins between yourself and the fish is the standard advice, and it is standard because those teeth go through a fin and a foot.
The trigger of the name is mechanical: the first dorsal spine locks upright and can only be released by a second, smaller spine behind it, letting the fish jam itself into a hole so tightly that nothing can pull it out.
The genus. Balistoides Fraser-Brunner 1935 - -oides (having the form of Balistes). ETYFish
The species. Balistoides viridescens (Bloch & Schneider 1801) - greenish. ETYFish
- heavy diamond-shaped body, each scale outlined like a tile
- dark moustache line above the mouth
- small eyes set high, swiveling independently
- nests in a crater in sand and will approach a diver
Why it's threatened
Exploitation impacts this species in parts of its range (e.g., Philippines; Lavides et al. 2010). It may also be impacted by ongoing coral reef degradation.
Threat classification from the IUCN Red List.
