The bluelashed butterflyfish, Chaetodon bennetti, is a species of butterflyfish (family Chaetodontidae). It is found in the Indo-Pacific from East Africa to the Pitcairn Islands, north to Japan and south to Lord Howe Island and Rapa Iti.
It grows to a maximum of 20 cm (almost 8 in) long. The body is yellow with a black patch surrounded by a blue circle below the dorsal fin and two curved blue lines above the belly. Its vertical black eyestripe is flanked by two blue lines.
Like the other butterflyfishes with angular yellow bodÃes with black eyestripes and (except in the present species) a single differently-colored patch, it belongs in the subgenus Tetrachaetodon. Among this group it seems to be the most basal living species. If Chaetodon is split up, this subgenus would be placed in Megaprotodon.
The bluelashed butterflyfish is found in seaward and lagoon reefs in areas with rich coral growth. Juveniles may be found in shallow Acropora thickets. Adults occur in pairs. This species feeds largely on coral polyps.