Also known as Bulbnose Unicornfish, Doctorfish, Humphead Unicornfish, Hump-headed Unicornfish, Humpnose Unicorn, Hump-nosed Unicornfish, Lancetfish, Thorntail, Thorntail Fish.
Found singly, or in small schools over coral reefs.
They feed on algae and zooplankton.
Length - 60cm
Depth - 2-40m
Widespread Western Indian Ocean
Surgeonfish have a blade like spine in the tail that points outwards when bent, unicorns have two hook-like plates along the tail, these are used for defence and are as sharp as a surgeons scalpel, hence the name "Surgeonfish".
Some species are venomous. Ref: https://www.fishbase.se/summary/Naso-tonganus