Chaetodon triangulum
Look for a chevron-patterned reef fish across the Maldives' atolls, warm water 28-30C year-round, usually spotted solo or in pairs.
Small, deep-bodied fish around 11 cm with a white flank crossed by bold black diagonal stripes that form a triangular chevron pattern, giving the species its name. A black band runs through the eye, and the fins carry a soft yellow trim. Body shape is the classic laterally flattened butterflyfish disc, easy to pick out against open reef.
Usually spotted picking around coral heads and reef structure alone or in a loose pair rather than in groups, moving steadily rather than darting. It keeps a comfortable distance from divers without bolting for cover, so patient, slow approaches give the best look. Most logs describe it as an uncommon sighting rather than a guaranteed one, so a find is worth pausing for.
Like most butterflyfish it pairs off with a single partner and the two are often seen holding a patch of reef together, a habit that makes a lone sighting worth a second look for its mate nearby.
No clear seasonal pattern shows up in the sightings, and with water sitting in a narrow 28.3 to 29.9C band across its range, it is a year-round reef resident rather than a seasonal visitor.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
This one is most reliably logged across the Maldives, especially the Northern, Central and Southern Atolls, where it turns up on reef slopes and drop-offs in good numbers. Outside the Maldives it is also a solid find in Thailand around Phuket, Koh Phi Phi, Koh Lipe and Khao Lak, with smaller but consistent populations in Myanmar's Mergui Archipelago, Indonesia, Malaysia and India.
Mapping where Triangle Butterflyfish is logged…
The Maldives is the standout location, with sightings spread across the Northern, Central and Southern Atolls. Thailand's Andaman coast, including Phuket, Koh Phi Phi, Koh Lipe and Khao Lak, is another dependable region, along with Myanmar's Mergui Archipelago.
There is no strong seasonal pattern in the sightings, so it is considered a year-round fish on the reefs it inhabits, consistent with the stable warm water it favours.
Look for a small white-bodied butterflyfish with bold black diagonal stripes forming a triangular chevron across the flank, a black eye band and yellow-edged fins. It sits at around 11 cm and has the typical flattened, disc-shaped butterflyfish body.
They stay small, reaching around 11 cm, which is a typical size for a reef-associated butterflyfish and keeps them easy to overlook against busy coral backgrounds.
No. They pose no threat to divers and are simply a small carnivorous reef fish that keeps its distance while feeding around coral.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
