Elongate Fangjaw, Sigmops elongatus Günther 1878

Other Names: Bristlemouth, Elongate Lantern-fish, Elongate Portholefish, Elongated Bristlemouth, Elongated Bristlemouth Fish, Longtooth Anglemouth, Long-tooth Anglemouth

An Elongate Fangjaw, Sigmops elongatus, from off the Three Kings Islands, South Norfolk Ridge, Tasman Sea, 213-214 m. Source: Robin McPhee & Mark McGrouther / NORFANZ Founding Parties. License: All rights reserved

A black bristlemouth with a broad dark silvery midlateral stripe on the head and along the side, dusky fins with small black spots, and transparent outer parts on the pectoral and pelvic fins. Individuals undertake daily vertical migrations to feed in upper layers of the ocean at night. The rows of photophores along the underside provide countershading or camouflage from predators and prey. 
This species was previously known as Gonostoma elongatum.

Cite this page as:
Bray, D.J. 2018, Sigmops elongatus in Fishes of Australia, accessed 24 May 2024, https://fishesofaustralia.net.au/home/species/1745

Elongate Fangjaw, Sigmops elongatus Günther 1878

More Info


From off central New South Wales, around southern Australia, to the Arafura Sea off the Northern Territory. Elsewhere the species is circumglobal in tropical to temperate waters - usually at depths of 500-1500 m during the day, migrating vertically to feed at night in 25-325 m. Smaller individuals usually occur in shallower waters than adults.


Dorsal fin 11-15; Anal fin 27-32; Vertebrae  39-41; Branchiostegal rays 12-13. Dorsal adipose fin present. 


Feeds mostly at night in the upper layers of the ocean. Food items include zooplankton, especially zoocrustaceans such as ostracopods and copepods, and small fishes.


A protandrous hermaphrodite - undergoes a sex change from male to female during the lifecycle. Spawning occurs year round, and females only reproduce once in their lifetime. Photophores develop in individuals over 6-22 mm SL. This species lives for less than two years. 


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

Species Citation

Gonostoma elongatum Günther 1878, Ann. Mag. Nat. Hist. (Ser. 5) 2 (7/8/9)(art. 2/22/28): 187. Type locality: South of New Guinea, Challenger station 191, depth 800 fathoms. 


Bray, D.J. 2018


Australian Faunal Directory

Elongate Fangjaw, Sigmops elongatus Günther 1878


Ahlstrom, E.H., Richards, W.J. & Weitzman, S.H. 1983. Families Gonostomatidae, Sternoptychidae, and associated stomiiform groups: development and relationships. p. 184-198. In Moser, H.G. et. al. (eds) Ontogeny and systematics of fishes. Spec. Publ. 1, Am. Soc. Ichthyol. Herpetol. Allen Press, Lawrence, KS.

Clarke, T.A. 1978. Diel feeding patterns of 16 species of mesopelagic fishes from Hawaiian waters. Fishery Bulletin 76(3): 495-513.

Fisher, R.A. 1983. Protrandric sex reversal in Gonostoma elongatum (Pisces: Gonostomatidae) from the Eastern Gulf of Mexico. Copeia 1983(2): 554-557.

Gill, T.N. 1883. Diagnosis of new genera and species of deep-sea fish-like vertebrates. Proceedings of the United States National Museum 6(380): 253-260 (p. 256, as Sigmops stigmaticus)

Gorelova, T.A. 1981. Notes on feeding and gonad condition in three species of the genus Gonostoma (Gonostomatidae). Journal of Ichthyology 21(5): 82-92.

Günther, A. 1878. Preliminary notices of deep-sea fishes collected during the voyage of H.M.S. Challenger. Annals and Magazine of Natural History 5 2(2, 22, 28): 17-28, 179-187, 248-251

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. Gonostoma elongatum. The IUCN Red List of Threatened Species 2015: e.T18252718A42691754. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T18252718A42691754.en. Downloaded on 3 March 2017.

Lancraft, T.M., Hopkins, T.L. & Torres, J.J. 1988. Aspects of the ecology of the mesopelagic fish Gonostoma elongatum (Gonostomatidae, Stomiiformes) in the eastern Gulf of Mexico. Marine Ecology Progress Series 29(27): 27-40 PDF available
Miya, M. & Nishida, M. 2000. Molecular systematics of the deep-sea fish genus Gonostoma (Stomiiformes: Gonostomatidae): two paraphyletic clades and resurrection of Sigmops. Copeia 2000(2): 378-389.

Miya, M., Yamaguchi, M. & Okiyama, M. 1995. Midwater fishes off the Pacific coast of Boso Peninsula, central Japan: species composition, abundance, biomass, and zoogeographic affinities. Japanese Journal of Ichthyology 42(3/4): 237-248.

Watson, W. 1996. Gonostomatidae: bristlemouths. p. 247-267. In H.G. Moser (ed.) The early stages of fishes in the California Current Region. California Cooperative Oceanic Fisheries Investigations (CalCOFI) Atlas No. 33. Allen Press, Inc., Lawrence, Kansas. 1505 pp.

Quick Facts

CAAB Code:37106004

Behaviour:Vertically migrates

Biology:Bioluminescent, hermaphrodite

Conservation:IUCN Least Concern

Depth:25-1500 m

Habitat:Mesopelagic, bathypelagic

Max Size:28 cm TL

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CAAB distribution map