Common name: Slickheads



A large and diverse group of deepsea fishes with mostly slender bodies, soft watery flesh, dorsal and anal fins opposite and far back on the body and either naked skin or large cycloid scales.

Members of four alepocephalid genera are bioluminescent, and the number and distribution of photophores differs between genera. The bioluminescence is thought to be intrinsic, as luminous bacteria are not associated with the photophores.

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Dianne J. Bray, Slickheads, ALEPOCEPHALIDAE in Fishes of Australia, accessed 15 Jul 2024,

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Family Taxonomy

The Alepocephalidae currently comprises 93 species in about 17 genera worldwide (Eschmeyer & Fong 2012). At present, 16 genera with 39 described species are known from Australian waters, although more than 50 species in 20 genera are thought to occur here.

Family Distribution

Slickheads inhabit meso- and bathypelagic waters over the continental slope, oceanic ridges and oceanic rises of all oceans. One species is known from the epipelagic zone, and a few species live on the abyssal plains. Some alepocephalids are found close to the bottom, whereas others live several hundred metres above it. Slickheads are found in depths between 100-5900 m, mostly between 500-3000 m.

Family Description

Soft, fusiforme somewhat laterally compressed fishes, rarely elongate, eel-like or deep-bodied. Head small to very large, snout variable from short, obtuse to beak-like or tubular; mouth large, maxillae longer than eye diameter, very long in some, eyes moderate to large, most with large aphakic space (elliptical pupil extending in front of lens). Jaws usually overlapped by some of the circumorbital bones. Teeth vary in size, shape and placement; gill openings usually wide, gill rakers long, numerous, upper elements of the two posterior gill-arches form an expanded pouch (crumenal organ) on each side involved in trapping food particles; no shoulder sac apparatus. Dorsal and anal fins usually far back on body, dorsal fin rarely in advance of anal fin, pelvic fins abdominal, caudal fin separate, forked, procurrent rays extending onto caudal peduncle, adipose fin absent. Scales cycloid, variable, head usually naked and covered in smooth, filmy black skin; body either naked or with large, thin, cycloid scales; photophores present in a few genera.

Family Size

Although alepocephalids reach 1.5 metres in length, most are between 200-500 mm SL.

Family Feeding

Little is known of slickhead biology. They reportedly feed on macroplanktonic invertebrates, including jellyfishes, salps, pyrosomes and ctenophores. A few species are predatory carnivores that feed on fishes and cepahlopod molluscs, and some smaller species may feed on mesopelagic crustaceans, such as euphausiids, decapods and mysids.

Family Reproduction

Very little is known of slickhead biology, including reproduction. Fecundity is low, and females lay large eggs (between 2 and 8 mm in ovaries), most probably near the bottom. Larval development is direct.

Family Commercial

Alepocephalids are of little commercial importance and there are no specialised alepocephalid fisheries. They are, however, taken as bycatch in deep-sea trawl fisheries, and some temperate and subtropical species occur in sufficient numbers to be sold commercially.

Family Conservation

IUCN Red List: Not evaluated.

Family Remarks

Many live in small groups or schools. Slickheads lack a swim bladder and rely on their soft, watery flesh for buoyancy; a few species may undertake diurnal migrations.


Dianne J. Bray


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