Ecsenius midas
Golden, eel-like and easy to miss: find Midas Blenny on reefs around Khao Lak, Thailand, in warm 25-29°C water year-round.
A slender, eel-like body about 9 cm long, usually golden-yellow to orange with a faint dark stripe running through the eye. It hovers in open water near its burrow rather than perching flat on rock like most blennies, with a constant undulating swim that catches the eye. The long dorsal fin runs nearly the full length of the back, giving it a streamlined, almost fangblenny-like silhouette.
Look for it hovering a body length or two above a reef crevice or coral head, drifting with a loose, snake-like swimming motion rather than resting on the substrate. It darts back into its hole the moment a diver gets too close, and pairs or small groups often share a patch of reef. Most sightings are on the open reef face during daylight dives rather than tucked into rubble or sand.
Its swimming style and yellow colouring closely mimic fang blennies and small wrasses that feed on parasites, letting it slip past predators and territorial reef fish that would otherwise chase off a blenny.
Sightings show no clear season, and with a comfortable range of 24.6 to 29°C it stays active on these reefs year-round.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged around Khao Lak in Thailand, where it turns up at more sites than anywhere else in the data. Smaller but consistent populations are logged around Ponta do Ouro in Mozambique and along the KwaZulu-Natal coast of South Africa.
Mapping where Midas Blenny is logged…
Khao Lak in Thailand is the most consistent spot in diver records, with smaller populations logged around Ponta do Ouro in Mozambique and the KwaZulu-Natal coast of South Africa.
There's no strong seasonal pattern in sightings. It favours water between 24.6 and 29°C, which holds year-round on the reefs where it's found.
Look for a small golden-yellow to orange fish, around 9 cm, hovering above the reef with a loose, eel-like swim instead of resting on rock. A faint dark eye-stripe and a long dorsal fin running the length of its back help confirm it.
They top out around 9 cm, making them one of the larger blennies you'll spot but still an easy fish to overlook on a reef.
It mimics the swimming style and colouring of cleaner-type fang blennies and wrasses, which helps it move around the reef without being harassed by territorial fish or predators.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Klipfish
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