An Indian Ocean unicornfish with orange lips and blue and orange fin margins, and no horn.
To 45 cm standard length, so longer including the tail filaments; commonly 35. Despite the name, adults have no horn and the head profile is smoothly rounded. The body is grey-brown with a yellow patch on the forehead and a bold black and yellow mask around the mouth. The dorsal fin is yellow with a blue line at its base and a black band above that. The anal and pelvic fins are dark brown. There are two fixed bright orange plates on each side of the base of the tail, and the tail is notched, with long trailing filaments from each corner in adult males.
This species was for a long time lumped with the orangespine unicornfish, and the split matters here. This is the Indian Ocean fish and the correct name for the Maldives; the other is the Pacific fish. The visible difference is the dorsal fin: yellow in this species, dark in the Pacific one.
It browses leafy seaweeds on reef slopes and rocky bottom between 5 and 30 m, usually in pairs or small groups, rather than grazing filamentous algae the way most surgeonfish do. The two orange tail plates are fixed and do not fold away. They are scalpel-sharp and a thrashing fish can cut deeply, so do not grab the tail.
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.