Unicorn Leatherjacket, Aluterus monoceros (Linnaeus 1758)

Other Names: Smooth Leatherjacket, Unicorn Filefish, Unicorn File-fish, Unicorn Leather Jacket, Unicorn Leather-jacket, Unicorn Leatherjacket Filefish, Unicornfilefish, Yellow-finned Leatherjacket

A Unicorn Leatherjacket, Aluterus monoceros, at Fairy Bower, Sydney, New South Wales. Source: Richard Ling / Flickr. License: CC By Attribution-NonCommercial-ShareAlike

A large pale grey leatherjacket with faint spotting in adults, a long slender dorsal-fin spine, and a reticulate pattern of pale lines and greyish blotches in juveniles. While the Unicorn Leatherjacket usually occurs on outer reefs, individuals often shelter around floating debris and jellyfishes far out to sea.
Video of a Unicorn Leatherjacket at Osezaki, on the Izu Peninsula, Japan, depth 36 m.

Cite this page as:
Bray, D.J. 2019, Aluterus monoceros in Fishes of Australia, accessed 13 Jul 2024, https://fishesofaustralia.net.au/Home/species/792

Unicorn Leatherjacket, Aluterus monoceros (Linnaeus 1758)

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Garden Island, south Western Australia, around the tropical north to southern New South Wales; also Lord Howe Island in the Tasman Sea. Elsewhere, the species is circumglobal in tropical and subtropical seas. 
Usually inhabits outer reefs, occasionally found shallower near steep drop-offs or on deep reef sandflats. Juveniles are pelagic, and often shelter beneath floating objects such as logs, debris and jellyfishes.


Dorsal fin II, 45-52; Anal fin 47-53.
Body highly compressed, elongate; snout convex in adults; eyes positioned far back on head above pectoral-fin base; first dorsal-fin spine slender (second spine buried in skin); rudimentary pelvic spine disappears in large specimens.


Feeds on benthic invertebrates.


Taken as bycatch in commercial fisheries in parts of its range.

Species Citation

Balistes monoceros Linnaeus 1758, Systema Naturae 1 Ed 10: 327. Type locality: near Hong Kong and the West Indies.


Bray, D.J. 2019


Atlas of Living Australia

Unicorn Leatherjacket, Aluterus monoceros (Linnaeus 1758)


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Quick Facts

CAAB Code:37465022

Conservation:IUCN Least Concern

Depth:1-120 m

Habitat:Reef associated & pelagic

Max Size:75 cm TL

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CAAB distribution map