Description

Also known as Blackear Surgeonfish, Blackear Tang, Black Surgeonfish, Black Tang, Doctorfish, Golden-rimmed Surgeonfish, Golden-rimmed Tang, Goldrim Surgeonfish, Goldrim Tang, Gold-rimmed Surgeonfish, Gold-rimmed Tang, Grey Surgeonfish, Grey Tang, Lancetfish, Powder Black Surgeonfish, Powder Black Tang, Powder Brown Surgeonfish, Powder Brown Tang, Powder Gray Surgeonfish, Powder Gray Tang, Thorntail, Thorntail Fish, Velvet Surgeon, Velvet Surgeonfish, Velvet Tang, Whitecheek Tang, White-cheeked Surgeonfish, White-cheeked Tang, Whiteface Surgeonfish, Whiteface Tang, White-tail Surgeonfish, White-tail Tang, Yellow-banded Surgeonfish, Yellow-banded Tang, Yellowfin Surgeonfish, Yellowfin Tang, Yellow-rimmed Surgeonfish, Yellow-rimmed Tang.

Found singly or in schools, over exposed lower surge zones,of hard bottomed clear lagoons and seaward reefs.
They feed on filamentous algae.
Length - 21cm
Depth - 0-65m
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.se/summary/Acanthurus-nigricans