A heavy triggerfish to 55 cm (22 in), dark brown-blue with yellow-edged fins, the juveniles patterned in bright blue wavy lines that fade as they grow. It works sand and rubble beside the reef rather than the coral itself.
It is an excavator. The fish blows water at the bottom and picks up stones in its teeth to move them, digging craters that can be a meter across in search of urchins, molluscs and crabs, and crushing them with a jaw built for the job. Other fish follow it for what the digging exposes, exactly as they follow a goatfish.
The same crater becomes a nest, and that is when it becomes a problem. A guarding female defends a cone of water that widens upward from the nest, and she will drive off anything inside it, divers included - the same geometry as the Titan Triggerfish, and the same answer: leave sideways and low, not up.
The trigger of the name is a lock. The first dorsal spine raises and is held by a second, smaller spine behind it, so the fish can wedge itself into a hole and cannot be pulled out.
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
- digs a wide crater in the sand and hangs above it
- length up to 55 cm
Why it's threatened
There are no known major threats.
Threat classification from the IUCN Red List.
