Distinctive Characters: Dorsal fin with 9 spines and 23-26 rays. Anal fin with 3 spines and 23-26 rays. Pectoral rays 17. Body depth about 2.3, snout 7.9-8.2 in standard length. Body moderately elongate. Mouth small. Caudal fin lunate.
Colour: Uniform chocolate brown; caudal fin white. A dark spot present at rear base of dorsal fin and another below axial of pectoral fin.
Habitat and Biology: Generally found in outer reef areas at depths up to 70 m. Occurs in loose aggregations. Feeds on zooplankton well above the substratum.
Remarks: Acanthurus thompsoni occurs in schools and is very common in current-swept reefs. A. phillippinus Herre is a synonym.