A small parrotfish with a red-orange band from the mouth and two black spots at the start of the dorsal fin in the terminal male.
To 28 cm, commonly 20, which makes it a small parrotfish. One mark works in both phases: a distinct white spot immediately behind the base of the dorsal fin. Learn that and the fish is named. Initial-phase fish are brown or greenish-brown with a dark blue cast on the back and sides, turning red on the belly. Terminal-phase males are green with a red line running from the corner of the mouth to below the back of the eye, which is the name, two small black spots above the pectoral fin, and yellow and orange marks on the base of the tail.
The redtail and redfin parrotfish are the confusion. The white spot behind the dorsal fin, and in terminal phase the two black spots above the pectoral, separate this one.
It grazes algae and seagrass between 2 and 20 m, usually alone. It is shy and moves constantly, so it is harder to photograph than its neighbours. Females change sex to male.
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.