Black at a distance and iridescent blue-green close to, with a white line at the base of each dorsal and anal fin. It feeds up in the water above the reef edge.
To 50 cm, commonly 30. At a distance it looks flat black. In good light it is deep blue-black to blue-green, with faint lines of black spots along the scale rows and thin blue lines radiating from the eye across a yellowish forehead.
The mark that works in poor light is a bright pale blue-white line running along the base of the dorsal fin and along the base of the anal fin. The Indian triggerfish, which shares the Indian Ocean, has white at the edge of the tail instead of at the fin bases. The pinktail triggerfish has a white or pink tail and clear white fins.
It lives on clear seaward reef, usually near a drop-off, between the surface and about 75 m and mostly above 20 m. What sets it apart from other triggerfish is that it feeds up in the water column on plankton and drifting algae, often well off the bottom in loose groups; that behaviour is the best cue at range. It nests in sand and will defend the nest, though it is far less aggressive than the titan triggerfish. It is uncommon in most places and abundant around isolated oceanic islands, which is the pattern on this site: uncommon and mostly deep in Florida, common in the Bahamas, Cayman and at Revillagigedo.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.