Six black bars, shallow water, and grazing in mobile groups that overwhelm territory holders.
To about 27 cm, pale silver-green to white with five narrow black vertical bars plus a sixth short bar at the tail base and a black mark above the pectoral fin. It is the plainest and most numerous of the shallow surgeonfishes and among the easiest to identify.
It grazes filamentous algae on reef flats and shallow slopes, and does so in mobile schools of tens to hundreds. The schooling is a feeding tactic: a group entering the algal territory of a damselfish or another surgeonfish is too numerous to be driven out, and the whole school feeds while the territory holder attacks individuals. The behaviour is easy to watch in three metres of water and is one of the more legible pieces of reef ecology available to a diver. Recorded from the surface to about 20 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.