An eel-like sabre-toothed blenny with alternating light and dark bands on the yelllowish-brown head and body, and a blue-edged spot on dorsal fin behind the eye. Hairtail blennies have long-based dorsal and anal fins that are continuous with the tail fin, and large sabre-like fangs in each jaws. The Hairtail Blenny usually lives in the burrows of other fishes, and divers usually only see the head poking out.