Siganus virgatus
Yellow-faced reef fish common off Peninsular Malaysia and Koh Tao, comfortable in 25-29C water year-round.
Safety warning
Don't handle or corner this fish: the dorsal, anal and pelvic spines deliver a venomous sting that causes sharp, lasting pain if you're jabbed. Sightings are passive and low-risk if you simply watch from a comfortable distance and keep hands off the reef substrate it's feeding on.
If you're stung
Venomous fin spinesGeneral first-aid guidance, not a substitute for professional medical care. In an emergency, call your local emergency number.
Look for a laterally flattened, oval-bodied fish around 21cm with a bright yellow flank fading to blue-grey toward the tail, crossed by fine blue pinstripes. The giveaway is on the head: two dark diagonal bars, one running through the eye and one across the snout, giving the fish its common name. It swims with a slow, almost hovering motion low over the reef, usually alone or in a loose pair.
Most divers find it picking at algae and weed on coral rubble or sandy reef flats, moving unhurriedly and staying close to cover rather than out in open water. It tends to hold a bit of distance from divers but rarely bolts, letting you get a decent look if you approach slowly. Pairs are more often logged than large groups, and sightings run through the day rather than being tied to a particular light window.
Like other rabbitfish, it carries venomous spines in its dorsal, anal and pelvic fins, an unusual defence for a fish that otherwise looks like a harmless grazer.
No clear season shows up in the sighting data, and with a comfortable range of roughly 25 to 29C it holds station on tropical reefs all year, so any month works at its core range countries.
This is a reliable sighting across Peninsular Malaysia's east coast and Sabah, and it turns up widely through Thailand at sites like Koh Tao and Koh Chang. It's also well logged in the Philippines (Palawan and the Visayas), Bali in Indonesia, and Okinawa and the Ryukyu Islands in Japan, with smaller but steady numbers in Australia, India and Sri Lanka.
Mapping where Doublebar Rabbitfish is logged…
Strongest populations are logged along Peninsular Malaysia's east coast and in Sabah, with plenty more sightings around Koh Tao and Koh Chang in Thailand, Palawan and the Visayas in the Philippines, Bali in Indonesia, and Okinawa in Japan.
There's no strong seasonal pattern in the data, and its comfort range of roughly 25 to 29C keeps it on the reef year-round in its core Southeast Asian and Japanese range, so it's a fair bet on most trips.
They carry venomous spines in the dorsal, anal and pelvic fins that can cause a painful sting if you grab or corner one. Left alone, they're not aggressive and simply drift off if you keep your distance.
Check for a yellow-flanked, oval-bodied fish around 21cm with fine blue lines and two dark diagonal bars crossing the head, one through the eye and one over the snout. It moves slowly and low over the reef rather than darting.
They typically reach around 21cm in length, a modest reef fish rather than a large one.
Despite looking like a mild algae-grazer, it defends itself with venomous spines in its dorsal, anal and pelvic fins, the same trick used across the rabbitfish family.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
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