Bighead Portholefish, Margrethia obtusirostra Jespersen & Tåning 1919

A Bighead Portholefish, Margrethia obtusirostra - Australia. Source: Australian National Fish Collection, CSIRO. License: CC BY Attribution-Noncommercial

Body silvery on sides, darker above, with a dark caudal peduncle and caudal-fin base, a silvery gill cover, and dark anterior rays of the dorsal and anal fins. Bighead Portholefish have photophores along the entire ventral surface,

Cite this page as:
Dianne J. Bray, Margrethia obtusirostra in Fishes of Australia, accessed 21 Mar 2023,

Bighead Portholefish, Margrethia obtusirostra Jespersen & Tåning 1919

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Meristic features: Dorsal fin 15-16; Anal fin 23-25; Pectoral fin 14-16; Pelvic fin 8-9; Gill rakers 14-16; Pseudobranch 8-10; Vertebrae 33-34; Branchiostegal rays 16. 
Photophores (adult): absent on isthmus; OA and SO absent; ORB 1, OP 3, BR 11–12 (13), IV 12–13 (14) + 2, VAV 4; AC (12) 13 + 4 (3–5) = (16) 17, (12) 13 over anal fin.
Body moderately elongate; mouth large; gill filaments longer than first ceratobranchial gill rakers; gill rakers on hypobranchial; anal-fin origin slightly behind origin of dorsal fin, anterior rays of both elongate; last dorsal- and anal-fin rays split to base; dorsal adipose fin present; pelvic fins slightly in advance of dorsal fin origin. Swimbladder capacious. Scales deciduous.


Hermaphrodites, with the spawning season in summer-autumn; post-larvae sink gradually with development; photophore development is complete by about 27 mm SL.


Dianne J. Bray

Bighead Portholefish, Margrethia obtusirostra Jespersen & Tåning 1919


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

Badcock J. 1984. Gonostomatidae. pp. 284–301. In P.J.P. Whitehead MLB, J.-C. Hureau, J. Nielsen & E. Tortonese (eds). Fishes of the Northeastern Atlantic and the Mediterranean. Paris: Unesco. 1473 pp.

Fahay, M. 1983. Guide to the early stages of marine fishes occurring in the Western North Atlantic Ocean, Cape Hatteras to the Southern Scotian Shelf. J. Northwest Atl. Fish. Sci. 4: 1-423.

Okiyama, M. 1993. An atlas of the early stage fishes in Japan. Koeltz Scientific Books, Germany. 1154 pp.

Schaefer, S., R.K. Johnson & J. Badcock. 1986. Gonostomatidae. pp. 247-253. In M.M. Smith & P.C. Heemstra (eds) Smiths' sea fishes. Springer-Verlag, Berlin.

Quick Facts

CAAB Code:37106021


Depth:100-600 m

Habitat:Mesopelagic, bathypelagic

Max Size:8.3 cm SL

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