Also known as Blueline Surgeonfish, Blueline Tang, Blue-lined Tang, Cuvier's Surgeonfish, Doctorfish, Greyhead Surgeonfish, Lancetfish, Pacific Blueline Surgeonfish, Thorntail, Thorntail Fish.
Found singly or in small schools over mixed coral, pavement, rubble and sandy substrates of clear lagoons and seaward reefs.
They feed on algae.
Length - 25cm
Depth - 1-90m
Widespread Indo 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.in/summary/Acanthurus-nigroris.html