Most surgeon fishes graze on benthic algae and have a long intestine; some feed mainly on zooplankton or detritus.
Surgeon fishes are able to slash other fishes with their sharp caudal spines by a rapid side sweep of the tail.
Very small ctenoid scales. A small terminal mouth with a single row of close-set teeth. All have a deep compressed body with the eye high on the head and a long preorbital bone. Single unnotched dorsal fin with 4-9 spines and 19-31 rays; anal fin with 2 (only Naso) or 3 spines and 19-36 rays; pelvic fins with 1 spine and 3 (Naso and Paracanthurus) or 5 rays
Greek, akantha = thorn + oura = tail