A dark brown damselfish scattered with bright blue spots, densest on the head and back, up to about 11 cm (4.3 in). Juveniles are the most striking - almost jewelled - and the spots dull as the fish grows.
What makes it worth watching is the farming. Each fish holds a small patch of dead coral and tends the algae growing there, weeding out species it does not want and chasing off anything that comes to graze - other damselfishes, surgeonfishes, urchins, and divers who linger. The result is a visibly greener, shaggier patch than the rock around it, and a reef covered in such patches looks mottled from above. Eggs are laid inside the territory and guarded by the male, which is when the charging becomes most determined.
How to recognise it
- dark brown body scattered with bright blue spots
- spots brightest on the head and back, fading with age
- stays on one small patch and returns to it
- length up to 11 cm
