The common Red Sea parrotfish, rust-brown as a female and blue-green with pink markings as a terminal male.
To 41 cm, commonly 25. Initial-phase fish are rusty brown, which is the name, with light and dark banding and a clean yellow tail, and they are usually in groups of mostly females. Terminal-phase males are bright and multicoloured, mostly blue-green, with pink or orange scale edges and blue-green markings on the face and beak.
The rusty-brown body with a yellow tail is the reliable Red Sea mark for the initial phase. Separating terminal-phase males from the other Red Sea parrotfish is genuinely difficult and needs a close look at the face bands.
It grazes algae on coral reef between 1 and 60 m. Terminal-phase males hold harems, and feeding intensity changes through the year with water temperature. Its range is the Red Sea and Gulf of Aden east to the Arabian Gulf, Oman and Socotra, so it is close to a regional endemic.
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.