Bicolour blenny

About Bicolour Blenny

The Bicolour Blenny is a popular marine aquarium fish recognised for its striking two-tone colouration, with a dark brown to black front half and a yellow-orange rear section. Its comical personality and habit of perching on rocks make it a favourite for reef aquariums.

Bicolour Blennies spend much of their time perched on rockwork, darting between hiding spots and grazing on algae growing across the aquarium. They are excellent algae grazers, although they should not be relied upon as the sole method of algae control.

A mature reef aquarium with established live rock and natural algae growth is ideal. Supplement their diet with marine algae-based foods and quality prepared foods, particularly in aquariums where natural algae is limited.

They are generally peaceful towards other fish but can become territorial towards other blennies or similarly shaped bottom-dwelling species. Plenty of rockwork with caves and crevices helps provide suitable territory.

Bicolour Blennies are reef safe and generally leave corals alone, making them an excellent addition to many marine community and reef aquariums.

Quick Care Guide

Scientific Name: Ecsenius bicolor
Common Name: Bicolour Blenny / Bicolor Blenny
Family: Blenniidae
Type: Marine Fish
Adult Size: Approximately 11 cm
Temperament: Peaceful to Semi-Territorial
Care Level: Easy to Intermediate
Minimum Aquarium: 75 L+
Temperature: 24–28°C
pH: 8.0–8.4
Salinity: 1.023–1.026 SG
Diet: Herbivore / Omnivore
Tank Level: Bottom to Midwater
Suitable For: Reef aquariums, marine community tanks and mature systems

Frequently Asked Questions

Are Bicolour Blennies reef safe?

Yes. They are generally considered reef safe and typically leave corals and invertebrates alone.

Do Bicolour Blennies eat algae?

Yes. They naturally graze on algae and biofilm growing on rockwork. However, a varied supplemental diet is still recommended.

Can I keep multiple Bicolour Blennies together?

Generally, it is best to keep one per aquarium, particularly in smaller systems. They can become territorial towards other blennies.

What do Bicolour Blennies eat?

Provide marine algae-based foods, spirulina preparations, algae sheets and quality marine pellets. They will also graze naturally on algae and biofilm.

Do Bicolour Blennies need live rock?

They benefit greatly from mature rockwork containing natural algae and plenty of caves and crevices for hiding and perching.

Common Mistakes

Adding one to a brand-new aquarium
They benefit from an established aquarium with naturally growing algae and biofilm.

Keeping multiple blennies in a small tank
They can become territorial towards other blennies and similarly shaped fish.

Relying entirely on natural algae
If the aquarium doesn't produce enough algae, provide regular supplemental feeding.

Not providing enough rockwork
Caves, holes and perching areas are important for their natural behaviour.

Ignoring their jumping ability
Blennies can jump when startled, so a secure lid or suitable tank design is recommended.