Raises a fin twice the height of its body when it needs to look larger.
To about 40 cm, banded alternately in dark brown and pale yellow-grey with fine speckling, a yellow snout on adults, and dorsal and anal fins so tall that a fish with them raised is roughly circular and about twice its normal height. The display is used against rivals and predators. Juveniles are brighter, more strongly banded and are found in very shallow rubble and reef flats.
It grazes leafy and filamentous algae, mostly alone or in pairs, and works across a wide area of reef. It is not shy but keeps moving, and the fins are usually folded; the photograph worth waiting for is a confrontation between two fish, when both raise everything. Recorded from about 2 to 35 m.
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.