Fish
Bluespine Unicornfish
Naso unicornis
A large olive surgeonfish with a forward-jutting horn and vivid blue tail-base keels, grazing algae on Indo-Pacific reefs south to Natal.
- Typical size
- Reaches 70 cm
- Habitat
- Coral reefs and rocky shores
The bluespine unicorn is a big surgeonfish, light olive in colour, with a tapering horn projecting in front of the eye in adults and two pairs of bony, blue-keeled plates on the tail base that serve as slashing defences. The dorsal and anal fins carry fine blue lines, and males grow longer horns and tail filaments than females.
Reaching 70 cm, it ranges across the Indo-Pacific and south to Natal, living on coral reefs and rocky shores. It grazes benthic algae and, for such a large fish, will push into surprisingly shallow water.