Appearances of fishes can indeed be deceiving. To take one look at the longnose butterflyfishes, you'd expect them to be in the same hardiness category as the pinnatus batfish. Such is definitely not the case. If you are careful to select an individual that has not been beaten up physically and/or emotionally through collection and transport, these yellow beauties do exceptionally well in marine systems.
Classification: Taxonomy, Relation With Other Groups
The butterflyfishes, family Chaetodontidae, should be familiar to aquarists. There are more than one hundred described species, with a few dozen offered to the hobbyist throughout the year. About half of these are outright unsuitable for aquaria, being finicky eaters, easily stressing to death, or overly susceptible to infection. Such is not the case with our longnoses here.
The two species are easily distinguished on the basis of relative snout length. F. longirostris is the "winner by a nose" as it's scientific name implies. What did Billy Shakespeare write; "What's in a (common) name"? There is another longnose butterflyfish in the literature, Chelmon rostratus; unfortunately it is not near as hardy as it's yellow brethren. Also, if you cruise the literature, you may find there are other longnose species in this genus (these are invalid junior synonyms) and black and brown color variants (they are the same species, with the same care) but we're not going into them here.
Natural and Introduced Range
F. flavissimus is found in most of the Pacific, Indo-Pacific and Red Sea; F. longirostris overlaps the shorter nose sympatriate over much of its range.
Most offered are four to six inches in overall length, tail to rostrum. A truly gargantuan specimen will be about ten inches.
Selection: General to Specific
These fishes are readily available, and at moderate prices. Though imported from the Philippines and Indonesian areas, my favorite specimens hail from elsewhere. If you can, pick up one from Hawaii (where its known as lau-wiliwili-nukunuku-oi-oi), or the Christmas or Marshall Islands. Good specimens are also collected from time to time from Mexico's Pacific coast on down.
Collecting Your Own
Can be done. The vast majority of specimens are captured by strategically placing a barrier/mist net, "driving" an individual into same, and hand-netting it off. Please be careful if you intend to grab one "on the fly" by spooking it out from hiding. Gashed and mouth-torn Butterflies rarely survive long in captivity.
Long noses, like most Butterflyfishes, inhabit broken reef areas where food and hiding space is plentiful, and circulation brisk. Your success with them will be commensurate with providing similar conditions in captivity.
Favored parameters are a pH of 8.0 to 8.4, temperatures in the high seventies, low eighties, and an artificially low specific gravity of 1.020. The latter to allow higher gas diffusion, concentration, and aid in reducing parasite loads. Keep the pH high and make frequent partial water changes.
It should be mentioned that these fishes display some unusual behavior. Don't be unduly surprised should you catch yours swimming or hanging upside down; or that it might "spit" water in your direction at the surface. Also, let me mention their blanched whitish appearance on being exposed to light from dark conditions; like sleep or removal from a shipping box. A loss of yellow during the day is a fast sign that you need to be looking for a cause; probably fright from bullying, or diminished water quality.
One last color note (I promise); check out the disruptive black bar over the fish's eyes and prominent 'eye-spot' at the tail for prospecting predators to bite at. Okay, I feel better.
Longnoses are stout fishes but do require clean, well-filtered water. Circulation cannot be too strong to suit them either; keep the water moving.
Giving these marine organisms open areas and rocks, coral where they can seek refuge in a hex or show type aquarium, results in better adjusted, longer lived specimens. The system should be no smaller than forty gallons, ideally with twenty or more gallons set aside per butterfly.
Can be problematical. These fishes are best kept one to a system. The best wholesalers keep their specimens in separate cubicles. Overcrowding is stressful, but does temporarily cut down on squabbling.
Simple enough. One suggestion: put your longnose in as one of the first fishes, maybe right after the damsels. They need to feel at home so as to get their share of offered foods.
Outside of quarreling with other longnoses, these fishes are peaceable. Be wary of placing them with larger predatory fishes however. I have seen them used as bait by island fisher folk, and can recount more than one tearful aquarium gulp-loss.
Reproduction, Sexual Differentiation/Growing Your Own:
The butterflyfishes are broadcast spawners, with young passing through an extended planktonic stage as peculiar tholichthys larvae. As yet, they have not been spawned, reared in aquaria.
Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes
Despite their looks, these B/F's accept all types of foods, frozen, fresh and prepared, with gusto. You'd think that their long "beaks" and priser-like teeth would be only suited for snipping out invertebrates from tiny crevices, but these fishes will try almost any size and shape of foods offered. It's best to defrost frozen items.
Please do include some meaty foods daily; bloodworms, shrimps, clams. These fishes are active, seeking food all day on the reef and in aquaria, and do well only when offered sufficient nutrition. Be wary of relying solely on one type of dry or frozen prepared food type.
Disease: Infectious, Parasitic, Nutritional, Genetic, Social
These fishes tend to be very infectious- and environmental disease resistant. They are more susceptible than "average" to marine "ich" (Cryptocaryoniasis); this is easily cured with copper remedies and specific gravity manipulation (lowering).
Two other all-too-often fatal complaints are so-called secondary bacterial infections most-often resultant from bad handling. The genus Vibrio is often cited as implicated, following a mouth, body "incident" due to user-failure. After a reddish area forms at the mouth, fin-ray base or body flank, there is almost no chance of recovery.
I'd really like to do my bit here for vastly reducing these losses; they result from beatings in the wild, the tank, shipping bags, and in-between. What To Do: Be Careful, don't wallop the fish; it's that simple. If/when you use a mesh-type net (some collectors use clear-bottom varieties), make sure it is one composed of soft, fine material. Longnoses have a real problem with getting their snouts and fin rays, principally the hard dorsal, anal and pelvics, snagged in coarse netting; resulting in tearing and infection. Real professional fish handlers gently cradle the fish in fine nets with their hand behind, when lifting from and to water to diminish thrashing.
Similarly, providing the right size, shape, orientation with an adequate amount of water in a shipping bag is important. Allow me to elucidate. The worst, though typical arrangement is to plop a specimen into a bag just large enough to accommodate the animal head to tail. No wonder it ends up with a broken, fungused snout, torn fins, and you with a punctured bag. What to do: grant the organism enough bag space to turn around, and either double-bag and ship in the dark, or provide a dark 'spacer' (even newspaper works) between bag layers. Wholesalers and transhippers who can scarce afford the space and weight that retailers and hobbyists can would do well to ship these fishes on their sides. Yes, I'm very serious. By placing the same (albeit too small) size bag on it's side, the butterfly will lay down, struggle far less; and therefore use less oxygen, produce less wastes, pierced bags... you know, less mortality. This is not pie-in-the-sky theory. I've done it; try it, it works.
There is a reason why these butterflies are ever-popular. They're gorgeous and they live in captivity. Don't let their frilly looks throw you. Learn what a good specimen looks like and you will be successful with these species. If ever there was a "first-timers" butterflyfish, these would be them.
Allen, G.R. 1979. Butterfly and Angelfishes of the world. Vol. 2. John Wiley & Sons, N.Y.
Allen, G.R. & Roger Steene. 1979. The Fishes of Christmas Island. Indian Ocean Spec. Publ. Aust. Nat. Parks Wildlife. Canberra.
Burgess, W.E. 1978. Butterflyfishes of the World. T.F.H. Publications. Neptune, N.J.
Campbell, Douglas. 1980. Marines: Their Care and Keeping, Butterflyfishes: Part Two. FAMA 11/80.
Chlupaty, Peter. 1978. Keeping Butterflyfishes. TFH 4/78.
Hunziker, Ray. 1992. The Ten Best Butterflies. TFH 2/92.
Kerstitch, Alex. 1977. Butterflies and Angels of the Sea of Cortez. Marine Aquarist 7:9, 1977.
Miklosz, John C. 1976. Hawaiian Butterflies. Marine Aquarist 7:2, 1976.
Parker, Nancy. 1976. Lemon butterfly. Marine Aquarist 7:7, 1976.
Refano, Joseph. 1985. Butterflies from Hawaii. FAMA 7/85.
Siegel, Terry. 1973. Butterflies. Marine Aquarist 4(2), 1973.
Teh, Anthony T.F. 1974. King Neptune's Daughter (about Chelmon rostratus. TFH 8/74.