Common name: Doublefin Frogfishes


The rare Tetrabrachium ocellatum, the only known species in the family, has close-set eyes protruding on top of the head and modified webbed pectoral fins fins, enabling these fishes to move about on soft substrates. Unlike most anglerfishes, their illicium has no lure.

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Cite this page as:
Dianne J. Bray, Doublefin Frogfishes, TETRABRACHIIDAE in Fishes of Australia, accessed 20 Jul 2024,

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Family Taxonomy

A monotypic family; Tetrabrachium ocellatum, the only known species.

Family Distribution

Western Pacific Ocean, around northern Australia, New Guinea, and Indonesia; demersal on soft muddy and fine sandy bottoms in inshore waters at 5-55 m.

Family Description

Body small, elongate, strongly compressed; head short, compressed, eyes small, close-set on top of head; mouth small, opening dorsally, jaw teeth small, recurved, depressible, in 1 or 2 rows; gill opening a small pore behind and below pectoral-fin base. First dorsal fin with 3 spines on head, soft dorsal and anal fins long-based, rays short, embedded in fleshy membranes; pectoral fins bilobed, upper lobe with 4 rays, lower lobe with 5 rays, its membranes connected to body and pelvic fin; caudal fin long, rounded. Illicium in front of eyes, free from second and third dorsal-fin spines, short, thin, tapering to a point, without a terminal esca. Skin smooth, naked.

Family Size

to 8 cm TL

Family Feeding

Presumably, like other anglerfishes, voracious ambush predators feeding on small invertebrates and other fishes.

Family Reproduction

Little known; tightly scrolled ovaries release eggs embedded in a large bouyant gelatinous mass which develop attached to dorsal-fin rays.

Family Commercial

Rare fishes of no commercial importance, occasionally collected in prawn fisheries.


Dianne J. Bray


Pietsch, T.W. 1981. The osteology and relationships of the anglerfish genus Tetrabrachium, with comments on lophiiform classification. U. S. Fish. Bull. 79(3): 387-419.

Pietsch, T.W. & D.B. Grobecker. 1987. Frogfishes of the World: Systematics, Zoogeography, and Behavioral Ecology. Stanford University Press, Stanford, xxii , 420 pp.

Pietsch, T.W. 1999. Tetrabrachiidae. Double-fin frogfish (anglerfish). Pp. 2016-2017, In Carpenter, K.E. & V.H. Niem. Species identification guide for fisheries purposes. The living marine resources of the western central Pacific. Batoid fishes, chimeras and bony fishes. Part 1 (Elopidae to Linophrynidae). FAO, Rome.

Pietsch, T.W. & Kenaley, C.P. 2005. Tetrabrachiidae. Tetrabrachium ocellatum. Four-armed frogfish. Version 28 October 2005 (under construction). in The Tree of Life Web Project,