🚚 Dry goods ship Australia-wide 🐠 Livestock — buy online, collect in store 🧪 In-store water analysis
Eastwood AquariumMarine only
SavedCart
Home  /  Fish profiles  /  Bicolour Blenny
Bicolour Blenny (Ecsenius bicolor)

Bicolour Blenny

Ecsenius bicolor
Reef SafeAlgae GrazerBeginner FriendlyLots Of Personality
Family
Blenny (Combtooth)
Care level
Beginner
Temperament
Peaceful
Reef safe
Reef safe
Max size
10 cm
Min tank
100 L · 26 gal
Origin
Indo-Pacific
Diet
Herbivore
Food
Nori, Marine algae, Spirulina, Mysis, Marine pellets
Currently out of stock →Join the waiting list

Overview

The Bicolour Blenny (Ecsenius bicolor), also known as the Two-coloured Blenny, is a pint-sized fish with an outsized personality. Its body is split between a blue-to-dull-brown front and a warm orange rear, and you'll usually spot it perched on the rockwork, peering out of a crevice with those big, expressive eyes before hopping to its next lookout.

Hardy, peaceful and reef-safe, it's a brilliant beginner fish that also happens to earn its keep — grazing film and hair algae off the rocks as it goes. Watching it dart between hidey-holes and claim a favourite perch never gets old.

It's widespread across the Indo-Pacific and undemanding to keep, asking for little more than a mature tank with plenty of rock and a varied, algae-based diet. For colour, character and a bit of natural algae control in one small package, it's hard to beat.

Compatibility

Toward the general community the Bicolour Blenny is peaceful and easygoing, mixing well with most calm reef fish — clownfish, cardinals, tangs and the like. It's a confident little character rather than a shrinking violet, but it doesn't go looking for trouble with unrelated species.

The caveat, as with most Ecsenius, is lookalikes and turf. It can get nippy toward other blennies, small gobies and dartfish, especially in tight quarters where they compete for perches and grazing space. As a rule, keep just one blenny of this type per tank unless the system is large, and give any similar-shaped tankmates their own territory. Avoid aggressive or much larger fish that might bully it.

Health & quarantine

The Bicolour Blenny is hardy and forgiving, one of the easier marine fish to keep, which is a big part of its appeal for newer reefers. A quiet quarantine period and a slow acclimation are still worthwhile to confirm it's feeding before it joins the display, and it settles fastest in a mature, established tank with natural algae growth to graze. Stable water quality and a varied diet are really all it asks for. As with all blennies, fit a secure lid — they're capable jumpers, particularly while settling in.

Frequently asked questions

Is the Bicolour Blenny reef safe?
Yes, with a minor caveat. It won't bother most corals or invertebrates and is a genuine asset for grazing algae. The one thing to watch is that an underfed individual may occasionally nip at LPS coral polyps or clam mantles — keeping it well-fed on algae-based foods all but eliminates that risk.
Will it control algae in my tank?
It's a good helper rather than a complete solution. It grazes film and hair algae off the rockwork and glass, which keeps growth in check, but it won't clear a serious outbreak on its own — and you should still feed it prepared greens so it stays properly nourished rather than relying on tank algae alone.
Can I keep more than one blenny?
Best to keep just one Bicolour (or one similar blenny) per tank unless the system is large. They can be territorial toward other blennies, small gobies and dartfish, squabbling over perches and grazing turf. With unrelated community fish they're peaceful.
Do I need a lid?
Yes. Like all blennies, the Bicolour is a capable jumper, especially when settling in or startled. A secure lid or mesh screen is strongly recommended to prevent avoidable losses.
Is it a good beginner fish?
One of the best. It's hardy, reef-safe, full of personality and easy to feed, and it doesn't need a large or complex setup — just a mature tank with plenty of rockwork, a secure lid and a varied, algae-rich diet.
Why does it keep changing which hole it lives in?
That's normal blenny behaviour. Bicolours perch and shelter in rock crevices and will often move between favourite lookout spots throughout the day, defending a chosen home hole to sleep in. Plenty of crevices in the aquascape lets it behave naturally and feel secure.

Care guidance is drawn from our own experience — every fish is an individual, so treat it as a starting point, not a guarantee. Not sure if a species suits your tank? Come ask us in store. New to the terms? Read the care-terms glossary.