Chaetodon wiebeli
White body, black diagonal bars, orange highlights. Uncommon but reliable on reefs around Koh Tao and Pattaya year-round in 20-30C water.
Compact, deep-bodied fish around 13 cm with a white to pale-yellow body crossed by two broad black diagonal bars, one running through the eye and one behind the head. A patch of orange-yellow shows along the dorsal and anal fin edges, and the tail carries a narrow black band near the tip. There is no false eyespot, so the real black-masked eye is the clearest single tell at a glance.
Usually spotted picking around coral heads and rubble patches alone or in loose pairs, moving steadily rather than darting, which makes it an easy fish to approach slowly for a photo. Divers most often log it as uncommon to common on a given reef, so it is not a fish you can count on every dive, but where it does turn up it tends to stick close to structure rather than open water. Like most butterflyfish it keeps a fairly consistent daytime routine, working the same patch of reef rather than roaming far.
The black bar through the eye is a real disguise trick shared across many butterflyfish, breaking up the outline of the eye so predators struggle to judge which end of the fish is the head.
No clear seasonal pattern shows up in the sightings data, and it sits comfortably across a wide 20.6-29.8C range, so it is a year-round reef resident wherever it occurs rather than a seasonal visitor.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged in Thailand, especially Koh Tao, Pattaya and Chumphon, which together account for the bulk of sightings. Beyond Thailand it turns up with fair regularity on reefs in Sumatra and Java in Indonesia, around Phu Quoc in Vietnam, Sihanoukville in Cambodia, and Peninsular Malaysia's east coast, with smaller populations noted in China, Hong Kong and Taiwan.
Mapping where Hongkong Butterflyfish is logged…
Thailand is the strongest bet, particularly Koh Tao, Pattaya and Chumphon. It also shows up regularly in Indonesia (Sumatra, Java), Vietnam's Phu Quoc, Cambodia's Sihanoukville and Malaysia's east coast.
There is no strong seasonal signal in the sightings, and it tolerates a wide temperature range from about 20.6 to 29.8C, so it is present on its home reefs year-round.
Look for a white body crossed by two bold black diagonal bars, one through the eye, plus orange trim on the dorsal and anal fins. Unlike many butterflyfish it has no false eyespot on the flank.
They reach around 13 cm, a typical size for a reef butterflyfish, and are usually seen at that size or slightly smaller on the reef.
No. They are harmless reef fish with no venomous spines or aggressive behaviour toward divers, and are safe to approach and photograph.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
