Small to very large eels, maximum length attaining to 375 cm. Body elongate. Dorsal profile of head above and behind eye raised. Eye well developed. Snout short to elongate. Mouth large, gape usually extending behind posterior margin of eye. Posterior nostril high on head, above or before eye, a simple pore or in a tube. Gill openings restricted to small round hole or slit. Dorsal and anal fins variously developed, continuous with caudal fin around tail tip. Pectoral and pelvic fins absent. Lateral line pores absent on body except for 1 or 2 above and before gill opening. Color: variable, from nearly uniform to distinctive patterns of spots, blotches bars, and/or reticulations.|
Similar families occurring in the area. Chlopsidae: posterior nostril low on snout or inside mouth. Ophichthidae: posterior nostril low on side of head, on lip, or opening inside mouth. Congridae: pectoral fin usually present.
Remarks. Muraenids usually known from tropical and subtropical seas, some species in or occasionally entering freshwater. Many are found in shallow waters, inhabiting rocks and coral reef (some in mud bottom to depths of 500 m).