Chestnut Blenny

Cirripectes castaneus, commonly known as the chestnut eyelash-blenny, is a species of combtooth blenny that inhabits the coral reefs of the western Pacific and 🌊 Indian Oceans. This small fish, reaching a maximum length of 9.2 cm (approximately 3.6 inches), thrives in tropical marine environments, often in waters with depths ranging from 1 to 32 meters (3 to 105 feet), though it is most commonly found between 1 and 10 meters (3 to 33 feet).

The chestnut eyelash-blenny is equipped with distinct fins and vertebral features. It has 11 to 13 dorsal spines, 13 to 15 dorsal soft rays, 2 anal spines, 14 to 16 anal soft rays, and 29 to 31 vertebrae. Its dorsal fin features a unique deep notch near the last spine, and the body depth is roughly one-third of its standard length.

The fish exhibits a wide variation in coloration based on geography. Males in the Chagos (🇮🇴 British Indian Ocean Territory) region show alternating light and dark brown bars with yellow dorsal spine tips, while those in the 🌊 Red Sea have narrow red bars on a brown background. In contrast, males in the Great Barrier Reef display pink and brown bars, while those in 🇫🇯 Fiji show brown bars on a grey or yellow background. Females often feature a reticulated pattern of wavy brown lines with pale spots, though some can be plain brown, particularly those from 🇿🇦 South Africa and 🇰🇪 Kenya. Their head and eyes are marked with lines and spots, accented by a distinct red ring around the iris and a yellow ring around the pupil.

This species is known for its ability to breathe air, a useful adaptation for life in wave-swept algal ridges or outer reef flats, where they are typically seen in small, loose groups. They prefer rocky and coralline substrates, often found in coastal waters and able to spawn via ovipary. Their eggs are adhesive and demersally attached to surfaces, while larvae float planktonically in shallow waters.

Cirripectes castaneus has a broad distribution across the Indo-West Pacific region, from the 🌊 Red Sea to 🇹🇴 Tonga, reaching north to southern 🇯🇵 Japan and south to Lord Howe Island. The species' name is derived from Latin and Greek, with "cirrus" meaning curl or fringe, and "castaneus" referring to the brown color reminiscent of chestnuts.