Deepsea Fangjaw, Sigmops bathyphilus (Vaillant 1884)

Other Names: Bristlemouth, Deepsea Lightfish, Spark Anglemouth

A Deepsea Fangjaw, Gonostoma bathyphilum, from seamounts in the Tasman Sea.. Source: Robin McPhee & Mark McGrouther / NORFANZ Founding Parties. License: All rights reserved

An intensely black fangjaw with very small photophores.

Cite this page as:
Bray, D.J. 2018, Sigmops bathyphilus in Fishes of Australia, accessed 23 Jul 2024,

Deepsea Fangjaw, Sigmops bathyphilus (Vaillant 1884)

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Off mid New South Wales, around southern Australia, to off Perth Western Australia. Eslewhere the species is fond worldwide in all oceans, in depths below 700 m, and more commonly below 2000 m. This species does not undertake diel vertical migrations.


Dorsal fin 12-14; Anal fin 22-24; Caudal fin 17; Pectoral fin 10-11; Pelvic fin 7-8; Gill rakers 24-27; Vertebrae 37.
Photophores: ORB 1; OP 1; BR 9; IV 11-12 + VAV 4-5 + AC 20-21 = IC 35-37; OA 14. (see the family Gonostomatidae treatment for photophore terminology).
Body shallow, depth 14-16% SL; head length 23-26% SL; eye very small 2-3% SL; teeth present on side of vomer and in a single row on palatine; scales absent.


A protandrous hermaphrodite, although sex reversal is not obligatory. The species is also sexually dimorphic, with ripe males developing large olfactory lobes and reaching smaller maximum sizes. Males reach a maximum size of 150 mm SL. Not all males develop into females; those females which develop directly, together with those derived from prematurely reversing males, may form an early maturing female group, spawning for the first time at about 110-120 mm SL. Hermaphrodites range in size from 52 to 133 mm SL, but most are <100 mm SL. Sex-reversal of ripe males may be a response to critical population density levels of ripe females. Spawning does not appear to be seasonal, and at any given moment all sexual categories are present in the population. Sexually mature individuals tend to be restricted to depths greater than 1,500 m (Badcock 1986).


Unlike Sigmops elongatus, the Deepsea Fangjaw does not undertake diel vertical migrations.

Species Citation

Neostoma bathyphilum Vaillant, in Filhol, 1884, La Nature, Paris No. 559: 184, fig. 1.  Type locality: Gulf of Gascony.


Bray, D.J. 2018


Australian Faunal Directory

Deepsea Fangjaw, Sigmops bathyphilus (Vaillant 1884)


Badcock, J. 1984. Gonostomatidae. In, Whitehead, P.J.P., Bauchot, M.-L., Hureau, J.-C., Nielsen, J. & Tortonese, E. (eds). Fishes of the north-eastern Atlantic and the Mediterranean. Paris : UNESCO Vol. 1 510 pp. figs.

Badcock, J. 1986. Aspects of the reproductive biology of Gonostoma bathyphilum (Gonostomatidae. Journal of Fish Biology 29: 589-603.  

Craddock, J.E. & Haedrich, R.L. 1973. The distribution of Gonostomatid fishes in the western Indian Ocean. Journal of the Marine Biological Association of India 15: 285-292.

Harold, A.S. 1999. Gonostomatidae: bristlemouths, pp. 1896-1899, in Carpenter, K.E. & Niem, V.H. (eds) The Living Marine Resources of the Western Central Pacific. FAO Species Identification Guide for Fisheries Purposes. Rome : FAO Vol. 3 pp. 1397-2068.

Harold, A. 2015. Sigmops bathyphilus. The IUCN Red List of Threatened Species 2015: e.T18252853A42691919. Downloaded on 25 May 2018.

Harold, A.S. & Gomon, M.F. 2008. Family Gonostomatidae, pp. 224-227, in Gomon, M.F., Bray, D.J. & Kuiter, R.H. (eds). Fishes of Australia's Southern Coast. Sydney : Reed New Holland 928 pp.

Kenaley, C.P. & Stewart , A.L. 2015. 65 Family Gonostomatidae, pp. 421-435, in Roberts, C.D., Stewart, A.L. & Struthers, C.D. The Fishes of New Zealand. Wellington : Te Papa Press Vol. 2 pp. 1-576.

Miya, M. & Nishida, M. 2000. Molecular systematics of the deep-sea fish genus Gonostoma (Stomiiformes: Gonostomatidae): two paraphyletic clades and resurrection of SigmopsCopeia 2000(2): 378-389.

Paxton, J.R. 1994. Families Gonostomatidae, Photichthyidae, Sternoptychidae. pp. 246-251 figs 221-224 in Gomon, M.F., Glover, C.J.M. & Kuiter, R.H. (eds). The Fishes of Australia's South Coast. Adelaide : State Printer 992 pp. 810 figs. 

Spanovskaya, V.D. & Grigorash, V.A. 1979. Gonostomatids (Fam. Gonostomatidae) of the Australian-New Zealand region. Trudy Instituta Okeanologii. Akademiya Nauk SSSR. Moskva 106: 57-68 figs 1-2 [in Russian]

Vaillant, L.L. 1884. In Filhol, H. Explorations sous-marines. Voyage du "Talisman". La Nature, Paris No. 559. 182-186 pp.

Quick Facts

CAAB Code:37106020

Conservation:IUCN Least Concern

Depth:700-3,000 m

Habitat:Mesopelagic, bathypelagic

Max Size:17 cm SL

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