Onegill Eel, Ophisternon bengalense McClelland 1844

Other Names: One-gilled Eel

Onegill Eel, Ophisternon bengalense. Source: Gerald R. Allen. License: all rights reserved


An eel-like fish found in thickly-vegetated brackish estuaries, lagoon and swamps in a few areas of northern Australia.

Identifying features:
Body eel-like, head flattened, eyes very small
A single slit-like gill opening on underside of head
Dorsal and anal fins reduced to skin folds
Pectoral and pelvic fins absent
Reddish-brown to blackish-green
Length of snout about half (or less than half) the length of the upper jaw.

Cite this page as:
Dianne J. Bray & Vanessa J. Thompson, Ophisternon bengalense in Fishes of Australia, accessed 27 May 2024,

Onegill Eel, Ophisternon bengalense McClelland 1844

More Info


Although widespread throughout the tropical east Indo-west Pacific, the species is known only from a few areas in northern Australia - from Goulburn Island, Northern Territory, and the Daintree River, Queensland.

Onegill eels inhabit brackish estuaries and nearby lagoons and swamps under tidal influence - usually living in burrows on muddy sediments in quiet thickly vegetated backwaters. They also enter the lower freshwater reaches of rivers.


Body eel-like; head flattened; a single slit-like gill opening on underside of posterior part of head; eyes small, visible through skin; anus in posterior half of body; dorsal and anal fins reduced to skin folds on posterior part of body.


To 55 cm TL, commonly to 20 cm.


Blackish-green to reddish brown with a purple tinge and dark spotting.


Little is known of the biology of this species - likely to be a protogynous hermaphrodite, laying large eggs in burrows in the soft sediment.


  • EPBC Act 1999 : Not listed
  • IUCN Red List : Least Concern
  • Species Citation

    Ophisternon bengalense McClelland 1844, J. Nat. Hist. Calcutta 5(18): 197, 200, pl. 11(1-2).

    Type locality - Bengal, India.


    Dianne J. Bray & Vanessa J. Thompson

    Onegill Eel, Ophisternon bengalense McClelland 1844


    Allen, G.R. 1991. Field guide to the freshwater fishes of New Guinea. Publication No. 9 of the Christensen Research Institute, Madang, Papua New Guinea. Pls. 1-18: 1-268

    Allen, G.R., Midgley, S.H. & Allen, M. 2002. Field Guide to the Freshwater Fishes of Australia. Perth : Western Australian Museum 394 pp.

    Coates, D. 1993. Fish ecology and management of the Sepik-Ramu, New Guinea, a large contemporary tropical river basin. Environmental Biology of Fishes 38(4): 345-368.

    Dahanukar, N. 2010. Ophisternon bengalense. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <>. Downloaded on 23 November 2012.

    McClelland, J. 1844. Apodal fishes of Bengal. Journal of Natural History. Calcutta 5(18): 151-226 pls 5-14

    Pethiyagoda, R. 1991. Freshwater fishes of Sri Lanka. The Wildlife Heritage Trust of Sri Lanka, Colombo.

    Pusey, B.J., Kennard, M.J. & Arthington, A.H. 2004. Freshwater Fishes of North-eastern Australia. Collingwood, Victoria : CSIRO Publishing 684 pp.

    Pusey, B.J., Kennard, M.J. & Bird, J. 2000. Fishes of the dune fields of Cape Flattery, northern Queensland and other dune systems in north-eastern Australia. Ichthyological Explorations of Freshwater 11(1): 65-74

    Talwar, P.K. & Jhingran, A.G. 1991. Inland Fishes of India and adjacent countries. Oxford-IBH Publishing Co. Pvt. Ltd., New Delhi.

    Quick Facts

    CAAB Code:37285002


    Conservation:IUCN Least Concern

    Habitat:Brackish & freshwater swamps

    Max Size:55 cm TL

    Species Image Gallery

    Species Maps

    CAAB distribution map