Bicolor Blenny

The Bicolor Blenny is a small, hardy combtooth blenny (family Blenniidae) in the genus Ecsenius, common throughout the Indo-Pacific. Its name refers to the sharp division of its body into a dark front half and bright orange rear half, though coloration can vary somewhat by region and mood. It is a bottom-dwelling reef fish that shelters in small crevices and abandoned holes, and it is one of the most frequently kept blennies in the marine aquarium trade due to its algae-grazing habits and easygoing nature. Wild populations are widespread and considered stable.

• Small, elongated, cylindrical body typical of combtooth blennies
• Sharply divided two-tone coloration: dark brown/black front two-thirds, bright orange to yellow rear third
• Blunt head with large, high-set eyes and small fleshy cirri above each eye
• Single long, low dorsal fin running most of the body length
• No scales; smooth skin texture
• Reaches about 8-11 cm

Distinguished from other Ecsenius blennies by the clean, sharp boundary between its dark front and orange rear coloration.

Bicolor Blennies live on shallow coral and rocky reefs, rubble zones, and lagoons throughout the Indo-Pacific, from the Red Sea and East Africa to the central Pacific. They are typically found at depths of 1-20 m in warm, clear tropical water, favoring areas with abundant small holes, empty worm tubes, or rubble crevices that serve as shelter. They rarely stray far from a chosen refuge hole, darting out to feed and quickly retreating when disturbed.

This blenny grazes on algal film and small invertebrates from rock surfaces near its shelter, using a characteristic darting, hopping swimming style rather than continuous cruising. It is territorial and will defend its chosen crevice against other blennies and small intruders, often perching at the entrance to watch for threats before quickly retreating inside. Bicolor Blennies are typically solitary outside of pairing for spawning, when a male attracts a female to his shelter hole for egg-laying and subsequently guards the demersal eggs until they hatch.