Plain-bodied females in fast-moving shoals; the terminal male is green, yellow and magenta.
To about 16 cm. Females and initial-phase fish are pale with a broad dark stripe along the side and a white belly, and form fast-moving shoals of dozens over shallow reef. Terminal males are strikingly different — a green head, a broad magenta and yellow band behind it and a blue-green rear body — and are usually alone within a shoal of females.
It feeds on zooplankton in the surge zone above shallow reef, moving continuously, and is one of the most numerous fish in the top ten metres on exposed reef. Spawning happens daily in the early afternoon at the reef edge, with groups rushing upward to release eggs. It never holds still, and photographs are made by picking a spot and waiting rather than by following. Recorded from the shallows to about 15 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.