Harlequin Filefish, Oxymonacanthus longirostris (Bloch & Schneider 1801)

Other Names: Beaked Leatherjacket, Beaked Leather-jacket, Coral Filefish, Longnose Filefish, Long-nose Leatherjacket, Longnosed Filefish, Orange Spotted Filefish

A Harlequin Filefish, Oxymonacanthus longirostris, at Mary Island, Solomon Islands. Source: Sally Polack / FishWise Professional. License: CC BY Attribution-Noncommercial-ShareAlike


A small slender greenish leatherjacket with rows of yellow spots and dashes along the sides and a small black blotch on the tail. Males have bristles on the tail base. Harlequin Filefish shelter amongst branches of Acropora corals at night. They not only resemble coral branches, but they also smell like them, enabling the filefish to remain undetected by nocturnal predators (Brooker et al. 2014).

Video of Harlequin Filefish spawning in an aquarium.

Cite this page as:
Bray, D.J. 2022, Oxymonacanthus longirostris in Fishes of Australia, accessed 15 Apr 2024, https://fishesofaustralia.net.au/home/species/812

Harlequin Filefish, Oxymonacanthus longirostris (Bloch & Schneider 1801)

More Info


Houtman Abrolhos to the Dampier Archipelago, and offshore reefs of north Western Australia, Ashmore Reef in the Timor Sea, and the far northern Great Barrier Reef and reefs in the Coral Sea, to the Solitary Islands, New South Wales; also Christmas Island in the eastern Indian Ocean, and the Lord Howe Province and Norfolk Island in the Tasman Sea. Elsewhere the species is widespread in the Indo-west Pacific: East Africa, Seychelles, Madagascar and Mascarenes east to Samoa, north to Ryukyu Islands and Ogasawara Islands, south to Australia, Lord Howe Island, New Caledonia and Tonga. 

Inhabits clear lagoons and seaward reefs with rich coral cover at depths to 35 m.


Dorsal fin II (2nd spine not visible), 31-35; Anal fin 29-32; Pectoral fin 11-12.

Body elongate, snout elongate, pointed; mouth small, terminal. First dorsal fin origin above eye; pelvic fin rudiment absent; males with slightly elongate bristles on caudal peduncle.


An obligate coralivore - usually feeds on polyps of Acropora corals. 


Forms monogamous pairs.


Although traded in the aquarium industry, Harlequin Filefish are very difficult to maintain in captivity. In the wild, this species feeds on the polyps of Acropora corals.


The Harlequin Filefish feeds solely on polyps of Acropora corals, and is therefore highly susceptible to habitat loss due to coral bleaching.


Following coral bleaching episodes at Christmas Island, Harlequin Filefish appeared to have disappeared Hobbs et al. 2010). Subsequently, however, Hobbs (2013) found that the Harlequin Filefish fed on Pocillopora corals at Christmas Island when Acropora corals were affected by coral bleaching.


The specific name longirostris is from the Latin longus (= long) and rostrum (= beak), in reference to the elongate snout of this species.

Species Citation

Balistes hispidus longirostris Bloch & Schneider 1801, Systema Ichthyologiae :464 (as Balistes hispidus var. longirostris). Type locality: East Indies.


Bray, D.J. 2022


Atlas of Living Australia

Harlequin Filefish, Oxymonacanthus longirostris (Bloch & Schneider 1801)


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Quick Facts

CAAB Code:37465062

Conservation:IUCN Vulnerable

Depth:1-35 m

Feeding:Feeds only on coral polyps

Fishing:Aquarium fish (difficult)

Max Size:12 cm TL

Max Size:Reef associated

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Species Maps

CAAB distribution map