Diagnosis: Distinguished from all other species by the mottled colour and the long dorsal fin, which begins closer to the gill opening than to the anus (Ref. 9828).

Description: Typical eel form with dorsal fin origin nearer to gill slit than to anus, distance from dorsal fin to anal 16-19% of total length (Ref. 52193). Head rounded; snout depressed; lower jaw protruded; gill openings small; maxillary toothbands with distinct longitudinal groove (Ref. 45563, 52193). Pectoral fin rounded; pelvic fin absent (Ref. 45563). Scales matted-like under skin (Ref. 45563).

Colouration: Adults have a brownish to black marbling on their back on a greyish yellow background; this colouration can fade away; white belly; younger specimens are greyish to orange and the marbling is less visible (Ref. 48622). Body colour brown speckles scattered on back, sides and fins; yellow between speckles and edge of pectoral fin; belly white or pale blue (Ref. 45563).