Divided front to back on a diagonal; the juvenile is a black fish with yellow spots.
To about 20 cm, with a dark purple-brown front third cut off along a clean diagonal from the dorsal fin to the belly, and a pale yellow-white rear. Juveniles are entirely different: black with rows of bright yellow spots, and they act as cleaners, working over larger fish at set places on the reef. The change begins at around 5 cm and passes through a spotted intermediate.
Adults hunt small crustaceans and molluscs on and around coral, usually alone, and range deeper than the juveniles. They are moderately shy and tend to keep a coral head between themselves and a diver. Juveniles at a cleaning position are far more approachable and stay put. Recorded from about 5 to 45 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.