This fish rearranges the sea floor to eat. It blows water at the bottom to strip the sand off whatever is buried, picks stones up in its teeth and carries them aside, and digs craters that can be a meter across to reach urchins, molluscs and crabs, which it then crushes in a jaw built for exactly that. Other fish trail it for what the excavation exposes, the same way they trail a goatfish.
The crater becomes the nest, and that is when the digging stops being a spectacle and starts being a problem. The nest is a shallow crater in sand or rubble, and the territory the female defends stands on it as a cone that widens toward the surface. Swimming up keeps you inside that cone the whole way, and swimming up and away puts you further in rather than further out. Leave sideways, stay low, keep the fish in sight, and put your fins between the two of you. At 55 cm (22 in) she is large enough to make the point.
Out of season it is a heavy, slow, dark brown-blue animal with yellow-edged fins working sand and rubble beside the reef rather than the coral itself. The juveniles look like something else entirely - yellow-brown, ruled with bright blue wavy lines that fade as the fish grows - and are regularly reported as a different species.
The trigger of the name is a lock. The first dorsal spine raises and is held there by a second, smaller spine behind it, so a fish that has wedged itself into a hole cannot be pulled back out until it releases the catch itself.
The genus. Pseudobalistes Bleeker 1865 - pseudo- (false). ETYFish
The species. Pseudobalistes fuscus (Bloch & Schneider 1801) - dark or dusky. ETYFish
- heavy dark brown-blue body with yellow-edged fins
- juveniles patterned with bright blue wavy lines on yellow-brown, fading as they grow
- digs a crater up to a meter across and hangs above it
- other fish follow it for what the digging exposes
- up to 55 cm
Why it's threatened
There are no known major threats.
Threat classification from the IUCN Red List.
