Midas Blenny

The Midas Blenny (Ecsenius midas) is a combtooth blenny in the family Blenniidae found across the Indo-Pacific and the Red Sea. Unlike many bottom-dwelling blennies, it swims well up in the water column near reef structure, and its color, often golden-yellow, is thought to mimic that of the Lyretail Anthias, a common reef basslet, providing it some protection through resemblance. It is not considered threatened and is a familiar sight to divers along steep reef drop-offs. Its unusual swimming behavior and mimicry make it a notable example of Batesian-like mimicry among reef fish.

Key identification points:

• Elongated, slightly compressed blenny body shape
• Coloration highly variable: bright golden-yellow, orange, blue-violet, or mixed forms
• Small cirri (fleshy projections) above each eye
• Single long dorsal fin running nearly the full body length
• Forked tail fin, unlike the rounded tails of many other blennies
• Adult size around 10-13 cm Its free-swimming, mid-water habit and resemblance to anthias basslets distinguish it from typical bottom-hugging blennies, though its blenny-shaped head and cirri confirm true identity on close inspection.

Midas Blennies are found along steep outer reef slopes and drop-offs, typically at depths of 3 to 40 m, often hovering near the reef face rather than resting on the bottom. Their range extends across the Indo-Pacific from the Red Sea and East Africa to the central Pacific. They favor areas with abundant crevices for quick retreat and are frequently observed near or mixed among schools of anthias in strong current areas along reef walls. Warm tropical reef water and structurally complex drop-off habitat are their preferred conditions.

Midas Blennies swim actively in open water near the reef face, a behavior atypical for blennies, and often associate closely with schools of similarly colored anthias, likely gaining protective mimicry benefits. They feed opportunistically on zooplankton picked from the water column as well as algae grazed from rock surfaces. When threatened, they dart quickly into a crevice or burrow for shelter. They are generally solitary or loosely associated with anthias schools rather than forming their own dense schools, and spawning follows the demersal egg-laying pattern typical of blennies, with eggs attached to a surface and guarded until hatching.