A small chromis divided cleanly in two: the front half dark chocolate brown, the rear half and tail white, with the boundary running vertically down the body. About 6 cm (2.4 in), and unmistakable at a glance in a family where most species are grey.
It lives in groups over branching coral on shallow reef flats and upper slopes, feeding on plankton and dropping into the coral when threatened - the whole group vanishing into the branches at once and reappearing a few seconds later. Eggs are laid on a cleared patch of hard bottom and guarded by the male. The species is common in the shallows here and often shares a coral head with damselfishes of several other species, all of them keeping their own vertical band of water above the same colony.
How to recognise it
- front half dark brown, rear half and tail white
- division between the two colours sharp and vertical
- in groups over branching coral in the shallows
- length up to 6 cm
