Dark brown with a yellow tail as an adult; the juvenile is deep blue covered in brilliant blue spots and is often taken for a different fish.
To about 21 cm. The adult is grey-brown with scattered iridescent blue spots on the upper body and a paler, often yellow tail. The juvenile is a different fish and was once described as a separate species: dark blue with intense iridescent blue spots and a clear or yellow tail, which is where the old name jewelfish comes from.
The dusky damselfish is the practical confusion and its tail is the same grey-brown as its body, where this fish’s tail contrasts.
Nought to a hundred and twenty metres, but usually the top ten. Juveniles sit among the branches of fire coral; adults hold shallow reef-top territories where fire coral is abundant. It eats algae, fire coral polyps and invertebrates, and it also cleans parasites off other fish. Spawning is at sunrise for about an hour, heaviest between the full and new moon, and the male guards and fans the eggs. Eating its own clutch has been recorded.
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.