Acanthurus leucopareius
A reliable find on Hawaii's reefs at 24.6-28.7C, year-round, with a white bar at the tail base for quick ID.
A dark brown to blackish body with a compact, oval, laterally flattened shape typical of surgeonfish, reaching about 17 cm. The giveaway mark is a bright white vertical bar just in front of the tail base, which stands out clearly against the darker body even in low light. Look also for the sharp spine at the base of the tail, tucked into a groove, which is the family's signature defensive feature rather than a fin ray.
Divers most often see it grazing alone or in loose groups over rock and reef surfaces, rasping algae off rock with its small mouth. It is not especially wary of divers and will often keep feeding as you pass, though it tends to dart for cover in reef cracks if approached too quickly. Most sightings are logged at moderate reef depths rather than in the shallowest surge zones.
Like other surgeonfish, it carries a folding scalpel-sharp spine at the base of its tail that it can flick out sideways as a defence, which is where the family name comes from.
Sightings show no clear seasonal pattern, and with a comfortable range of 24.6 to 28.7C, it stays active on Hawaiian reefs year-round rather than showing up only in a particular season.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
This is a reef fish most commonly logged in Hawaii, with sites spread right across the islands, and it turns up far less often at a handful of sites near Easter Island in Chile. If you are diving Hawaiian reef systems, this is one of the surgeonfish you should expect to tick off rather than search hard for.
Mapping where Whitebar Surgeonfish is logged…
Hawaii is by far the most reliable place, with sightings spread across dive sites throughout the islands. It has also been recorded at a smaller number of sites around Easter Island, Chile.
There is no strong seasonal pattern in sightings, so it is seen year-round. Water temperatures on the reefs where it lives stay in a comfortable 24.6 to 28.7C band throughout the year.
Look for a small, dark brown oval-bodied fish around 17 cm long with one clear feature: a bright white vertical bar right at the base of the tail. The rest of the body is otherwise plain and dark, which makes that bar easy to spot.
They typically reach around 17 cm in length, making them one of the smaller surgeonfish you will encounter on Hawaiian reefs.
No, they pose no danger to divers and are not aggressive. Like all surgeonfish they carry a sharp spine near the tail for defence against other fish, but this is not a threat unless the fish is handled.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Striped Surgeonfish
3,294 sites
