A sleek golden-yellow blenny with a lyre-shaped tail that swims out into open water like an anthias, unusual for a normally rock-bound family. Hardy, reef-safe, and full of personality, it is a superb beginner blenny that can shift its color to blend with anthias schools.
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Indo-Pacific: from the Red Sea and East Africa across to the western Pacific
Origin
Old World
Climate
🌴 Tropical
Water type
🌊 Marine
Family
Blenniidae
Genus
Ecsenius
Part of the Blennies
Blennies are small, bottom-dwelling marine fish with scaleless bodies, blunt heads, and big expressive eyes, often perching on rocks or peering out from holes. The aquarium trade favors them for their comic personalities, useful algae-grazing habits in many species, and suitability for nano and reef tanks.
From the minimum an animal needs to be kept humanely, up to the ideal setup. Bigger is almost always better — minimums are floors, not targets.
Photo coming soon
Minimum
Rocky reef with caves
30 gal / 110 L reef
Ecsenius midas is a goldenshrimpfish-mimic; perches on rock and swims with anthias. Provide caves, ledges, and a refugium for natural pod grazing. Peaceful except to other blennies.
Photo coming soon
Recommended
Mature reef with refugium
55 gal / 200 L+
Larger reef gives perch variety. Diet: spirulina, mysis, nori. Refugium pod supply keeps the blenny grazing and rounded in body condition.
Photo coming soon
Ideal
Tall reef with anthias school
100 gal+ / 380 L+ with anthias
Tall reef with strong flow and a small anthias harem — the blenny shoals with them. Best display behaviour and most natural swimming in this scale.
Life & growth stages
How this animal changes through its life — each stage often has its own care, diet and space needs.
Photo coming soon
Egg
Fish eggs are small, translucent spheres, often laid in clutches on plants, substrate, or in a nest — or carried/brooded by a parent in livebearing and mouth-brooding species. A dark eye spot and the curled embryo become visible inside as development progresses.
Photo coming soon
Fry
Newly hatched fry are tiny and semi-transparent, frequently still carrying a yolk sac that fuels them before they feed freely. They lack full fin structure and adult coloration, staying near cover until they can swim and forage on their own.
Photo coming soon
Juvenile
Juveniles look like miniature adults but with developing fins and muted or different markings; many species shift pattern and color as they mature. Growth is rapid at this stage given clean water and steady feeding.
Adult
Adults show the species' full size, finnage, and mature coloration, and are sexually mature. Many fish develop sex-specific differences in size, color, or fin shape, which can intensify during breeding.
Habitat & enclosure
House one in a tank of 30 gallons or more with generous live rock containing holes and crevices it can dart into and sleep in, since it retreats to a rocky hole tail-first when startled or at night. Unlike most blennies it also cruises open water, so it appreciates some mid-water swimming room as well as rockwork. A secure lid is advisable, as it can jump when alarmed.
Keep stable reef parameters: temperature 72-79 F (22-26 C), pH 8.1-8.4, salinity 1.023-1.026 specific gravity, with moderate flow. Lighting can follow coral needs, as the fish is unfussy about it.
Substrate
Fine sand over plentiful live rock is standard; the rock's holes and crevices are the critical feature, providing sleeping holes and refuges. Substrate type itself is not important to this swimming, perching blenny.
Equipment & setup
A reliable heater, moderate flow, and any reef lighting suit it, with a protein skimmer recommended on larger systems. A tight lid helps prevent jumping when the fish is startled.
Diet
An omnivore that leans more carnivorous than the herbivorous algae blennies. It feeds on zooplankton in the water column and grazes some algae, and in the aquarium readily takes frozen mysis and brine shrimp, copepods, finely chopped seafood, and quality marine flakes and pellets with both meaty and algae content. Feed two to three times daily.
Because it hunts plankton in open water, it generally has an easier time getting enough to eat than the pure grazers and adapts quickly to prepared foods. A varied diet keeps its golden color rich.
Behavior & temperament
Peaceful and fully reef-safe with corals and invertebrates, and friendly toward most tankmates, though it may chase other blennies or similarly shaped fish in a small tank, so keep just one. It is bold and outgoing once settled, hovering in the open and retreating to its hole only when threatened. It famously mimics and schools alongside lyretail anthias (Pseudanthias squamipinnis), even shifting its body color to match them and gain protection.
This active, social temperament makes it more visible than a typical hole-dwelling blenny. It rarely bothers corals, clams, or inverts, making it an easy reef community fish.
Health
Hardy and disease-resistant for a marine fish, but still vulnerable to marine ich and velvet, so quarantine and drip-acclimate new arrivals. Its scaleless skin is sensitive to copper medications and poor water quality, so favor reef-safe treatments and keep parameters stable.
It usually feeds readily, which lowers the starvation risk seen in pure-grazer blennies, but a varied diet still matters for color and condition. Stable salinity and temperature and a low-stress tank keep it thriving for years.
Tips, DIY & hacks
If you want to see its anthias-mimicry, keep it alongside a small group of lyretail anthias and watch it school and shift color. Provide at least one deep rocky hole it can claim as a bolt-hole and bedroom, which helps it settle in fast. It is one of the most beginner-friendly, personality-rich blennies for a peaceful reef.
