Filefishes III

/The Conscientious Marine Aquarist

Filefishes, Family Monacanthidae

By Bob Fenner

Monacanthus tuckeri

Genus Monacanthus: Four species. Great beauties as juveniles, adults. soooo

Monacanthus tuckeri Bean 1906, the Slender Filefish. Western Atlantic; North Carolina to the Antilles. To four inches in length. This three quarter inch juvenile hanging out in a gorgonian in the Bahamas.

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Genus Oxymonacanthus: Two species. Rarely live for any length of time in captivity. Obligate corallivores.

Oxymonacanthus longirostris (Bloch & Schneider 1801), the Harlequin Filefish or Orange Spotted Filefish in the aquarium interest. The most commonly offered member of the family... and rarely alive for more than a week in captivity. In the wild almost only eats Acropora polyps.
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Genus Paraluteres: Two species. Neat, small species that are hardier than most of the family.

Paraluteres prionurus (Bleeker 1851), the Blacksaddled Filefish. Indo-Pacific, but not the Red Sea. To four inches in length. A mimic of the Sharpnose Puffer, Canthigaster valentini. Juvenile in N. Sulawesi, Aquarium and Maldives adult specimens.

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Genus Paramonacanthus:

Paramonacanthus japonicus (Bleeker 1853), the Japanese Filefish. Indo-West Pacific. To four inches in length.

Genus Pervagor: Eight species. The best genus of Files for captive use.

Pervagor janthinosoma Redtail or Blackbar Filefish. Indo-W. Pacific. To 14 cm. Mauritius 2016.

Pervagor melanocephalus (Bleeker 1853), the Red-Tailed Filefish. Indo-West Pacific. To six inches in length. One of the best Files for captive use.

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Pervagor nigrolineatus (Herre 1927), the Blacklined Filefish. Western Pacific: Japan to Western Australia and the Solomon Islands. To 10 cm. in length. Raja Ampat pic. http://fishbase.org/Summary/speciesSummary.php?ID=4371&genusname=Pervagor& speciesname=nigrolineatus

Pervagor spilosoma (Lay & Bennett 1839), the Fantail Filefish. Eastern Pacific, principally Hawai'i where it's occasionally shipped out of. To seven inches overall length. Feeds on algae and benthic invertebrates, including corals. Hawai'i photo.

Genus Pseudalutarius:

Pseudalutarius nasicornis (Temminck & Schlegel 1850), the Rhinoceros Filefish. Generally found in calm waters amongst seagrasses, soft corals, hiding vertically when approached. Indo-West-Pacific; South Africa (into the Atlantic there) over to Indonesia, Australia. To 19 cm. N. Sulawesi image. http://fishbase.org/Summary/speciesSummary.php?ID=7979&genusname=Pseudalutarius &speciesname=nasicornis

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Genus Pseudomonacanthus: Four species.

Pseudomonacanthus macrurus (Bleeker 1856), the Strapweed Filefish. Indo-West Pacific; Indian Ocean, South China Sea, PNG. In N. Sulawesi.

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Pseudomonacanthus peroni (Holland 1864), Peron's Filefish. Indo-West Pacific; Indonesia, Bali to N. Australia. To ten inches in length. Here in N. Sulawesi.

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Genus Scobinichthys: Monotypic. Thrown in here for diversity's sake.

Scobinichthys granulatus (White 1790), the Rough Leatherjacket. Indo-West Pacific, Australia. To twelve inches in length. This one in the London Aquarium, U.K.

Natural Range

Filefishes occur in shallow reef and rocky areas in Atlantic, Indian and Pacific marine environments. Though often present, sometimes in large numbers, they are frequently missed by noisy, unobservant divers.

Most files reach around 15cm. (six inches to us old timers); one gets to a maximum length of one meter; Aluterus scriptus. Now that's a big file!

Selection: General to Specific Healthy specimens are characterized by good color, without blotchy or necrotic patches, behavioural elements (curiosity, activity), and active feeding.

Most species make excellent captives, except unfortunately the often-offered long nosed or orange-spotted filefish (Oxymonacanthus longirostris). This one only eats coral polyps. Leave it in the ocean if you can't provide adequate care. In fact, I think the whole genus is corallivorous and should be avoided.

A few notes on filefish capture for the aqua-venturer. Commercially, small individuals are taken with hand nets at night or net-dragged out/over eel grass and such. Larger specimens are taken in mesh fish traps and barbless hook and line baited with some sort of tasty meat.

Environmental: Conditions

Habitat

Filefishes rely a great deal on subterfuge to avoid predation. Relatedly, they seem to prosper in physical surroundings that complement their gaudy integuments. Real or artificial decor schema that allow a blending/camouflaging of files makes them feel at home. Provide them homes where they can appear inconspicuous.

Chemical/Physical

Not picky. Natural water or no. Relatively insensitive to changes, high or low specific gravities, metabolite build-ups...

Display

Give them plenty of opportunities for hiding and wedging into caves and crevices like triggers.

Behavior: Territoriality

This whole Order is best characterized as very individualistic. In general, filefishes are docile toward members of the same species and their family members when small or necessarily temporarily crowded (at the Dealer's); but watch out! They can become overtly intolerant without any apparent provocation. Most are best kept one file to the tank.

Introduction/Acclimation

Placing of most filefish species and specimens is unceremonious. Quinn suggests his favorite "drip" method of blending "old" shipping water with "new" system water. I'll still plug my raw freshwater dip method to prevent/dilute pest, parasite and pollution introduction. (See next few Sections)

Monacanthids are not touchy in terms of handling stress. They typically "brighten up" shortly after introduction, displaying curiosity about their new digs.

A caution concerning netting files; their skin and fins get stuck but good in most consumer nets. It's much better for all parties to do away with nets and "hand-lift" specimens or scoot them into a container underwater if/when they have to be moved.

Predator/Prey Relations

The group are opportunistic omnivores, bordering on tiger barb nippiness in saltwater equivalency. Keep your eye on them, though they usually cause little outright damage, being followed and chewed on continuously can get on one's nerves. Shown, the biting end of a Barred Filefish, Cantherhines dumerilii.

As for "turnabout is fair play", most wanna be predators find filefishes too tough to chomp. In addition to the height-increasing dorsal "trigger" mechanism, they share the triggerfish's capacity for slightly enlarging their bodies by expanding a ventral flap supported by a large movable pelvic bone.

Reproduction, Sexual Differentiation:

Some species have been observed spawning in the wild. Eggs are noted as green in color, about a millimeter in diameter, demersal (on the bottom), adhesive, hatching in a couple of days after sunset, becoming pelagic, planktonic larvae.

In some species, males are slightly larger and more colorful.

Locomotion:

Effected most of the time via undulations of the median fins. At times of need/desire, the tail comes into play for short past bursts of straight speed.

Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes

Most any and all frozen and fresh foods will sustain files. Meaty clams and crustacean foodstuffs will always shake one out of the doldrums. Don't neglect their need for vegetable material though.

Stomach contents analyses reveal a broad mix of hydrozoans, algae, Sedentariate Polychaetes, sponges, gastropods, amphipods, gorgonians, sea grass (a true vascular plant), colonial anemones and tunicates. Not good reef-tank candidates.

Disease: Infectious, Parasitic, Nutritional, Genetic, Social

Martin mentions the efficacy of using tetracycline HCL for treatment of "anomalous" bacterial anomalies, in his case presumed digestive infection manifest in non-feeding. He lists administering the antibiotic directly to the system water at 50 mg per gallon. Any medication advice from anywhere is to be followed in a separate treatment tank, not your main system.

Summary:

Filefishes are available seasonally and geographically. Don't let their shy, delicate appearance fool you, a few make interesting, affordable aquarium specimens.

Bibliography/Further Reading:

Barlow, G.W. 1987. Spawning, eggs and larvae of the Longnose filefish Oxymonacanthus longirostris, a monogamous corallivore. Environ. Biol. Fish.; vol. 20, no. 3 183-194. 1987.

Eristiwady, T. & P. Geistdoerfer. 1991. Biological aspects of Monacanthus tomentosus (Monacanthidae) in the seagrass beds of Kotania Bay, West Seram, Moluccas, Indonesia. Mar. Biol.; vol. 109, no. 1, 135-139. 1991.

Hauser, Hillary. 1984. Skin Diver Magazine's Book of Fishes. The Photographic Book Company. 1984.

Martin, Robert A. 1976. Scrawled filefish. Marine Aquarist, 7:6, 1976.

Nelson, Joseph S. 1976. Fishes of the World. John Wiley & Sons, Inc.

Quinn, John R. 1990. Fooling around with filefish. T.F.H. 10/90.

To: part I, part II,

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