African butterfly fish

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: plant safe.

Typically wild-caught; acclimate slowly.

Feeding

A surface insectivore with a large, upward-opening mouth. In the wild, almost everything it eats has fallen onto the water from above: insects, spiders, small terrestrial invertebrates. In an aquarium, live food gets the best response (wingless fruit flies, small crickets, spiders, mosquito larvae), and frozen bloodworm or brine shrimp offered at the surface film works well. Many specimens will eventually accept floating flake or pellets, but prepared food should not be the staple. Anything that sinks past the top centimetre of water gets ignored. Newly arrived fish often refuse food for the first week or two, and live fruit flies are the standard way to get them started.

Compatibility

• Sits motionless at the surface with pectoral fins spread and ambushes anything small enough to fit in the mouth. Neon tetras, small rasboras, and other tiny surface fish are food. Suitable tankmates are species too large to be swallowed that occupy lower water
• Aggressive toward other surface fish and toward conspecific males; in a roomy, heavily planted tank a small group can coexist but expect chasing
• Practical guideline is mid- and bottom-dwelling tankmates above eating size. Larger tetras and barbs work; for a West African biotope, Ctenopoma, elephantnoses, and Synodontis catfish are reasonable choices
• The long trailing pelvic filaments are an obvious target for fin-nippers, so tiger barbs, serpae tetras, and similarly inclined species should be avoided
• Wants a near-still surface. A filter outlet that ripples or breaks the top of the water disrupts its feeding posture

Origin and habitat

A surface-dwelling oddball from tropical Africa, and the last surviving member of the family Pantodontidae; Pantodon buchholzi is the genus' only species, with no close living relatives outside the broader osteoglossiform group that includes arowanas and the arapaima. It occupies the slow and still margins of freshwater habitats across West and Central Africa, with records from the Niger, Congo, and Ogooue drainages and Lake Chad, covering parts of Sierra Leone, Nigeria, Cameroon, Gabon, the Central African Republic, and both Congos. Its preferred water is shaded and weedy, often beneath floating vegetation in creeks, swamps, and quiet backwaters of lakes. Genetic work on the species has produced a startling result: fish from the Niger and Congo basins are essentially indistinguishable in appearance, yet their mitochondrial DNA differs by around 15 percent, a split estimated to be older than 50 million years (placing it in the Late Paleocene, on the order of 57 million years ago). That makes the species one of the more extreme examples of vertebrate morphological stasis on record and a likely cryptic-species case. Despite the common name, the wide pectoral fins are used not for gliding but for short, explosive jumps clean out of the water; the long trailing pelvic filaments hang down below the body. The fish breathes air at the surface and will drown if denied access to it. The genus name comes from Greek for 'all teeth' (pan + odous), and the species name commemorates Dr. Buchholz, who collected the type material. Peters described the species in 1877, and it entered the European aquarium hobby in 1905. Adults usually reach about 10 to 13 cm, occasionally 15 cm. IUCN Least Concern.

Breeding

Spawning in captivity is uncommon and tends to require deliberate triggering. The usual approach is to drop the water level to a few inches for a couple of weeks, then refill with soft and acidic water (around pH 6.5) at roughly 26 to 29C. After a prolonged chase among floating plants the male clamps onto the female and the pair spawns at the surface, often over several days; reports describe more than 100 eggs released per day. The eggs are clear at first, float, and darken within a few hours. The adults will eat their eggs given the chance, so they should be removed. Hatching times reported in the literature cluster around 2 to 4 days, with the lone outlier of about a week. Raising the fry is the difficult part: they only take the smallest mobile prey at the very top of the water, such as newly hatched brine shrimp, and will only strike at food drifting directly into their field of view. By about 12 weeks the young look like miniature adults, but full maturity takes a year or more. Sexing is done from below: in mature males the anal fin is modified, with elongated rays forming a tube-like structure used in fertilization, while females show a plain, rounded anal fin and a fuller body when carrying eggs.

Common problems

Most captive deaths are jumps out of the tank, not disease. The fish is a powerful jumper and can squeeze through surprisingly small openings around heater cords, filter intakes, and airline tubing, so the tank needs a tight-fitting cover with no gaps; reports of fatal escapes through openings only a couple of centimetres wide are common. The other recurring problem is food refusal, especially in newly imported wild-caught specimens. Live food usually breaks the fast (wingless fruit flies, small crickets, terrestrial insects, mosquito larvae), and once eating, most fish can be transitioned to frozen bloodworm and other surface foods over a few weeks. They will not chase food downward. Anything that sinks below the upper centimetre or so of the water column is ignored, so food has to be presented at the surface.

Bioload

Further reading

• Biotope aquariums: matching fish to their natural habitat