Also known as Blue-lined Sailfin Tang, Blue-lined Tang, Brown Sailfin Surgeonfish, Brown Sailfin Tang, Brown Sailing Tang, Brown Scopas Tang, Brown Tang, Brushtail Tang, Calico Scopas Tang, Calico Tang, Doctorfish, Hybrid Tang, Koi Scopas Tang, Lancetfish, Scopas Tang, Spotted Tang, Thorntail, Thorntail Fish, Tricolor Surgeonfish, Tricolor Tang, Twotone Surgeonfish, Yellow Sailfin Tang, Yellow Tang.
Found singly or in small schools, over lagoons and seaward reefs, rich in coral growth. Identified by the dark, almost triangular body with white spine. However sometimes these fish have different colours, as in the pics and these are now considered to be a hybrid of this species.
They feed on algae.
Length - 40cm
Depth - 1-50m
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/5951