Common name: Whalefishes


Whalefish life stages are so remarkably different, that they were previously not only placed in different families, but the males were placed in a different order. Johnson et al. (2009) used morphology and mitogenomic sequences to show that fishes previously placed the Mirapinnidae (hairy fishes, tape tails) and the Megalomycteridae (bignose fishes) are actually the larvae and males of the family Cetomimidae (whalefishes). Males undergo amazing morphological and physiological changes as they mature. Juvenile males feed on copious amounts of copepods and develop enormous livers to sustain them throughout their adult life. Unlike the females which have huge mouths to catch large prey, males cannot feed because they lose their stomach and oesophagus as they mature.

Whalefishes lack external scales and the pelvic fins are absent in females, usually absent in males and jugular in position in juveniles.

Cite this page as:
Dianne J. Bray, Whalefishes, CETOMIMIDAE in Fishes of Australia, accessed 02 Feb 2023,

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Family Taxonomy

A family of deep-sea fishes with about 9 genera and more than 45 species, many of which are undescribed.

Family Description

Larvae: Epipelagic. Some species have small mouths, hair-like growths on the body, very large pelvic and caudal fins. Others have an amazingly long caudal streamer that may resemble siphonophores or even look like a sea snake. Females: Mesopelagic fishes with huge mouths, tiny eyes, and a huge lateral line canal. The dorsal and anal fins are far back on the body, the pectoral fins are small, and they lack fin spines, pelvic fins, ribs and visible scales. Males: Nasal organs very well-developed, teeth, oesophagus and stomach absent.

Family Feeding

Larval whalefishes feed on tiny crustaceans (copepods).

Family Conservation

Not evaluated.


Dianne J. Bray


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Paxton, J.R. & Johnson, G.D. 2003. If tapetails and the hairyfish (Mirapinnidae) are larval whalefishes (Cetomimidae), bignose/mosaic-scale fishes (Megalomycteridae) should be male whalefishes. Abstr. Ann. Meet. Am. Soc. Ichthyol. Herpetol. 2003. 371 pp.

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