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Marine   Fishes

Harlequin filefish
(Oxymonacanthus longirostris)

Harlequin filefish

Alternative species (click on the thumbnail to see the card)

  • None (for the moment!)


Scientific name
Oxymonacanthus longirostris

Common name
Orange spotted filefish
Longnose filefish
Beaked leatherjacket
Harlequin filefish


what are its countries of origin?

Origin: Indian Ocean, South Pacific and Red Sea
Natural habitat: lagoons and coral reefs with clear waters (up to 30 meters deep or 100 feet deep)


what are the physical differences between males and females?

The male has a stronger color than the female. It is usually smaller.





what is the minimum volume for this species?

200 L / 44 Imp gal / 53 US gal in spécific
600 L /132 Imp gal / 158 US gal in community


what are the water parameters for the maintenance of this fish?

T°: 23 à 26°C or 73 to 79°F
pH: 7.5 to 8.5
Density: 1024 to 1028





what is the maximum size of this fish?

10 cm (4")


what is the average life expectancy of this fish?

8 years or more

Living zone

in which area of the aquarium does this fish live?



sociability of the species



How to feed the Orange spotted filefish?


How to feed the Orange spotted filefish?

Particularly difficult to feed, this lime-fish very rarely accepts traditional aquarium fish foods. In the wild, it feeds almost exclusively on corals of the Acropora type. In the context of captive maintenance, this is really the black spot of this species: many fish die prematurely because of an unsuitable diet or a particularly recalcitrant fish. Here is the summary for the life of the vast majority of specimens: they are caught in the wild (they do not breed in aquarium), arrive hungry and weak at the store and end up dying at home very quickly. What a shame for these beautiful creatures! We can only encourage you to avoid this fish that should stay in its natural environment!

Oxymonacanthus longirostris mangeant

You can give him artemia that it will shyly peck at, but if it eats only that, its diet will not be complete and it may suffer from deficiencies. May also be proposed: pieces of nereis, mold flesh, lobster eggs, Mysis, krill, Formula 1 glitter, Eeze, Life Spectrum Marine Fish Formula, IO Marine Blend... Dry food must be moistened with water the whole aquarium and data (in case of persistent recalcitrant, soak them in artemia juice). Some aquarists rub food on coral polyps for consumption. Finally, complete with a cut of Acropora that you will sacrifice from time to time!

If your fish are getting lean, they are not eating enough. Put an Acropora cuttings in an emergency in their aquarium if none of the previously mentioned solutions worked.

Meals will be distributed 2 to 3 times a day. You can add vitamin B to their food once a week, or concentrated enrichment solutions like Ultra Energizer or Selco for example.

Finally, note that the chance of proper feeding increases if you maintain a couple rather than an isolated individual.


What kind of behavior does the Orange spotted filefish have?


What kind of behavior does the Orange spotted filefish have?

The Harlequin filefish is peaceful and sociable with all other fish species. It is quite fearful overall and does not leave its territory. You will see a lot of interaction between members of this species.

It spends a lot of time upside down, distinctive and fun feature of this kind of fish.


Who can live with the Orange spotted filefish?


Who can live with Orange spotted filefish?

couple de Oxymonacanthus longirostris

In the wild, this fish evolves into a couple once an adult (the juveniles form groups). In captivity, it must imperatively be maintained in the same configuration: in pairs. Besides, any attempt to maintain it alone will end in failure.

Avoid cohabitation with corals of the Acropora type and with the molluscs on which it feeds.

By its timid nature, also avoid maintenance with aggressive or very territorial fish. Prefer non-territorial or territorial fish but of calm nature. Remember that the more space there is in an aquarium, the more the cohabitations will go well!


How to breed the Orange spotted filefish?


How to breed the Orange spotted filefish?

Impossible in the aquarium.

Its aquarium

Which aquarium for the Orange spotted filefish?

Its aquarium

Which aquarium for the Orange spotted filefish?

A reef aquarium made of rocks and corals will be perfect for its maintenance. However, be careful not to introduce those of the Acropora type because the lime-fish are striving and destroying them systematically. On the other hand, they seem to be losing interest in soft corals.

It will take at least 600 liters or 132 Imp Gal or 158 US Gal for a community aquarium. In specific, you can go with a tank of 200 liters or 44 Imp Gal or 53 US Gal per fish, then add 100 liters or 22 Imp Gal or 26 US Gal per additional fish.

Do not subject the lime-fish to too much current, which may deplete it and limit its movement. Also be careful of your suction pumps because they can get stuck in it: protect them!

Good To know

Find all additional information!

Good To know

Find all additional information!

This fish is very difficult to feed, fragile and should be reserved for a handful of marine aquarium experts (its maintenance requires high level skills and know-how). Indeed, the mortality rate is very high. We can only encourage you to avoid the purchase of this species because there is very little chance that you will manage to maintain it and that your fish will eventually die quickly. By avoiding buying it, not only will you avoid a disappointment purchase, you will save money and discourage the trade of these fish that ultimately have nothing to do in private aquariums. Let us think that some animals cannot be kept in captivity and leave this little wonder in its natural environment!

Oxymonacanthus longirostris dans la nature

It seems that young individuals acclimatize better to life in captivity than fish caught in adulthood that eventually die quickly.

Attention to its acclimatization: the one with orange spots is very sensitive to the variations of the parameters of water. Acclimatization should be slow and gentle. This will prevent the fish from becoming weak, fragile or ill. Note also its sensitivity to chemicals whose use should be carefully studied.

Its physical appearance is perfect camouflage to hide among the Acroporas it feeds. Another formidable weapon to its credit: it is able to diffuse different smells according to the situations. It can simulate the smell of the corals they rub shoulders to hide, or spread a smell reminiscent of toxic corals, or attract small crustaceans for its next meal.

This species is a cousin of the ballistae. It can be mistaken for Oxymonacanthus halli but it is smaller (7 cm or 2.76 inch) and has a shorter muzzle.

It owes its name of «lime» to its raspy skin recalling a file.

Oxymonacanthus longirostris dans son milieu naturel

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