Cantherhines dumerilii
Oval, leathery-skinned reef fish common off Hawaii and Reunion, easy to overlook in 24-29C water year-round.
Oval, deep-bodied and flattened side-to-side, growing to around 26 cm, with a small mouth set on a pointed snout that gives it a slightly beaked look. Colour runs grey-brown to olive with faint pale bars or blotches down the flanks, and the skin has a rough, sandpaper-like texture typical of filefish rather than smooth scales. Look for the thin, spine-like first dorsal ray it can raise and lock upright when it wants to look larger or wedge into a crevice.
Usually seen cruising slowly alone or in loose pairs over reef flats and rubble zones, picking at coral, algae and small invertebrates rather than schooling or racing around. It tends to hold a wary distance from divers, drifting off at an unhurried pace rather than bolting, and will often tuck into a ledge or crevice and lock its dorsal spine up if it feels cornered. Most logs describe it as an uncommon but steady find on the reef rather than something divers actively hunt for.
That raised dorsal spine is not just for show underwater: filefish use it to wedge themselves into a crack in the reef at night or when threatened, locking the spine so a predator cannot easily pull them back out.
No clear seasonal pattern shows up in the sightings data, and with a comfortable range of about 24 to 29C it turns up on tropical reefs across all months. Plan around good general reef conditions at your chosen destination rather than a particular season for this species.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged around Hawaii, which accounts for the bulk of sightings, with strong populations also off Reunion (Saint-Paul and Saint-Leu) and Mauritius (Grand Baie and Trou aux Biches). Further sightings come from Orchid Island in Taiwan, Bali in Indonesia, the Tuamotu Islands in French Polynesia, and reefs in Costa Rica and Guam.
Mapping where Barred Filefish is logged…
Hawaii offers the most consistent sightings, and it also shows up well around Reunion and Mauritius, plus Orchid Island in Taiwan, Bali in Indonesia and the Tuamotu Islands in French Polynesia.
There is no strong season in the sighting data, so it is a year-round find on reefs sitting in the 24 to 29C range it prefers.
Look for an oval, flattened body around 26 cm long with rough skin, faint pale bars, and a small beak-like mouth. The giveaway is the thin dorsal spine it can raise upright when alarmed.
They typically reach around 26 cm in length, a modest, hand-sized reef fish rather than anything imposing.
No, they are not considered dangerous to divers. They tend to keep their distance and their main defence, a locking dorsal spine, is used against predators rather than people.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Whitespotted Filefish
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