Bicolor Blenny

About the Bicolor Blenny

The Bicolor Blenny (Ecsenius bicolor) is a charming and entertaining addition to any reef aquarium, featuring a distinctive two-toned coloration that gives this species its name. The front half of the body displays purple to blue hues, while the rear half transitions to vibrant yellow or orange, creating a striking color contrast. These personable fish are known for their curious nature, comical expressions, and habit of perching on rocks to survey their territory.

Why Reef Keepers Love This Fish

• Unique Coloration: Distinctive two-tone appearance with purple-blue front and yellow-orange rear
• Entertaining Personality: Curious, interactive, and often perches in visible spots with endearing facial expressions
• Beginner-Friendly: Hardy, adaptable, and forgiving of minor water parameter fluctuations
• Reef-Safe: Won't harm corals or invertebrates, making it ideal for mixed reef tanks
• Algae Control: Grazes on nuisance algae, helping maintain a clean aquarium
• Small Size: Compact footprint makes it suitable for smaller reef systems
• Peaceful Temperament: Gets along well with most community fish and invertebrates

Care Requirements

Experience Level: Beginner to Intermediate
Temperament: Peaceful (may be territorial with other blennies)
Minimum Tank Size: 30 gallons
Diet: Herbivore—primarily grazes on algae but also accepts spirulina, marine algae, herbivore pellets, and occasional meaty foods like mysis shrimp
Max Size: 4 inches

Ideal Water Parameters

Temperature: 72-78°F
pH: 8.1-8.4
Salinity: 1.023-1.025 SG
Ammonia/Nitrite: 0 ppm
Nitrate: <20 ppm

Tank Placement & Behavior

Bicolor Blennies are rock-dwellers that love to perch on high vantage points where they can observe their surroundings. They'll claim a favorite spot—often a hole in the live rock or a cave—and use it as their home base. These fish have wonderful personalities and will often swim to the front of the tank to interact with you, displaying their characteristic "grumpy" facial expression that makes them so endearing.

While generally peaceful, they can be territorial with other blennies or similarly shaped fish. It's best to keep only one blenny per tank unless you have a very large system with plenty of rockwork to establish separate territories.

Feeding Tips

Bicolor Blennies are primarily herbivores that graze on microalgae throughout the day. Provide plenty of live rock with natural algae growth, and supplement with dried seaweed (nori), spirulina-based foods, and herbivore pellets. They'll also accept occasional meaty foods like frozen mysis shrimp. Feed small amounts 1-2 times daily, ensuring they have constant access to grazing opportunities.

What to Expect

Your Bicolor Blenny will arrive healthy and ready to acclimate. They may be shy initially but will quickly establish a favorite perch and become one of the most visible, interactive fish in your aquarium. Their quirky personalities, unique coloration, and helpful algae-grazing habits make them excellent additions to peaceful reef tanks. Watch for their amusing behavior as they dart in and out of rockwork and peer at you with their expressive faces!