Ecsenius yaeyamaensis
A 4cm reef dweller most reliably found on Malaysia's east coast, tucked into coral rubble in warm 26-29C water.
A tiny fish, barely 4 cm, with an elongated blenny body that tapers to a narrow tail and perches propped on its pelvic fins. Look for mottled brown-to-olive patterning broken by pale blotches or bars along the flank, and a blunt, almost comical face with high-set eyes. It sits still on rubble or dead coral rather than swimming in open water, which is often the giveaway before you can even make out the pattern.
Spends most of its time perched motionless on rubble, dead coral, or the reef substrate, blending in until it dashes a short distance to a new perch. It is not shy exactly, more indifferent, letting divers get close before it moves rather than bolting for cover. Most sightings are casual, on-the-substrate finds during a slow look at the reef floor rather than a dedicated search.
Like other Ecsenius blennies, it lacks a swim bladder, so it never hovers in midwater and always has some part of its body in contact with the reef, which is why patient bottom-scanning finds far more of them than mid-water searching.
No clear seasonal pattern shows up in the data, and with a comfortable range of 26.3 to 29.3C it's a year-round resident of the reefs it occupies 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 on Malaysia's Peninsular east coast, where the bulk of sightings come from. Smaller but consistent numbers turn up in Western Australia, around Dili in Timor-Leste, and in Indonesia's Raja Ampat and Sulawesi, with an occasional record from Palau's Peleliu.
Mapping where Yaeyama Blenny is logged…
Peninsular Malaysia's east coast is the strongest area for sightings, with additional records from Western Australia, Dili in Timor-Leste, and Raja Ampat and Sulawesi in Indonesia.
There's no strong seasonal signal in the sighting data, and the 26.3 to 29.3C temperature range it's found in holds steady year-round on these reefs, so any month works.
Look for a tiny, 4 cm blenny with a mottled brown and pale body perched still on rubble or dead coral rather than swimming. Its blunt face and habit of staying in contact with the substrate are the main clues underwater.
They stay small, topping out around 4 cm, which makes careful scanning of rubble and coral debris necessary to spot one.
No. They pose no threat to divers and simply perch on the reef, moving away a short distance if approached too closely.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
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