Oxymonacanthus Longirostris

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Latin name Oxymonacanthus Longirostris - (Bloch & Schneider, 1801)
Local name Harlequin filefish
Family Monacanthidae - Oxymonacanthus
Origin East Indian Ocean, West Indian Ocean, Australia, Japan, Indonesia, Central/West Pacific
Max length 12 cm (4,7")
As aquarium fish
Minimum volume 400 cm (106 gal)
Hardiness Average
Suitable for aquarium Experience, preparation and extra care required
Reef safe Not reef safe
Aggressiveness Mostly peaceful but might be aggressive towards similar species
Recommended Small polyp stone coral (SPS)
Maybee Small crustaceans (Krill, mysis, artemia...)
Beware of
Feeding problems

These fish normally eat for the most part, coral polyps, therefore problems can arise in captivity when trying to give it an alternative food.
It is therefore essential to be well prepared before acquiring them.
However well prepared, there will be a large percentage, that will die after a short time in captivity.

It may mean having to keep live acropora as food, in order to keep these fish alive whilst they are getting accustomed to alternative types of food.

Keep in mind
Lives in a pair

This species can live as a pair (male and female).

Hiding places

This species needs good hiding places, for example, between live rocks.

Requires plenty of space for swimming.

This species revels in swimming and requires an aquarium with ample space.

Initially shy

This species can be very shy when first introduced into a new aquarium.

More aggressive fish can be introduced after this species has acclimatized.

Descriptions and further reading
Family description (Monacanthidae)

Filefish (Monacanthidae) have a very characteristic appearance, but whether one likes them or not is a matter of taste. 

Some species are suitable for aquaria, although they will occasionally eat a coral or invertebrate. They are therefore not so well suited to coral tanks.
They are often used to fight glass anemones (Aiptasia) and Majano anemones. Pervagor nigrolineatus is especially good at this.

They need peace and quiet from both the aquarist and other fish, when adjusting to the tank life.

Be careful when catching them, as they easily becomes caught in the net.

Aquarium trade Yes
Distribution Indo-Pacific: East Africa south to Maputo, Mozambique (Ref. 4421) and east to Samoa, north to Ryukyu Islands, south to the southern Great Barrier Reef, New Caledonia, and Tonga. Replaced by <i>Oxymonacanthus halli</i> in the Red Sea.
English common names Longnose filefish
Longnosed filefish
Coral filefish
Harlequin filefish
Beaked leatherjacket
French common names Lime à taches oranges
Poisson lime à taches oranges
Danish common names Langsnudet filfisk
German common names Orangepunkt-Feilenfisch
References and further reading

About references

2010. Success with the Harlequin Filefish, Oxymonacanthus longirostris - Reef Builders (English)

Dave Wolfenden. 2013. Filefish: A bit of rough! - Practical Fishkeeping - (English)
Scott W. Michael. Can You Add Filefish to a Reef Tank? - Fish Channel - (English)
Bob Fenner. Filefishes, Family Monacanthidae, Part I, Part II, Part III - Wet Web Media - (English)
Scott W. Michael. Those Fabulous Filefish - Tropical Fish Hobbyist Magazine - (English)