Also known as Blue Surgeonfish, Doctorfish, Lancetfish, Powderblue Doctorfish, Powderblue Surgeon, Powderblue Tang, Thorntail, Thorntail Fish.
Found in small to large schools, over reef flats and upper seaward slopes, of clear coastal and island coral reefs.
They feed on benthic algae.
Length - 38cm
Depth - 0-25m
Widespread Indian Ocean, Western Pacific
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/1257