Clown killifish

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

An obligate surface feeder with a tiny upturned mouth. Live food gives the strongest feeding response: wingless and flightless Drosophila fruit flies, baby brine shrimp, mosquito larvae, daphnia, and microworms are all eagerly accepted. Frozen food (frozen baby brine shrimp, frozen cyclops, frozen daphnia, small-grade frozen bloodworm) works once the fish learns the cue and is taken without much complaint. Dry food is the awkward category: some individuals will pick at floating micro pellets or crushed flake, others refuse it outright, and fish that have only been on live and frozen food in trade often won't transition without weeks of patience. The fish takes food only from the upper centimetre of the water column and ignores anything that sinks, so a feeding ring or a small clear surface space between floating plants makes feeding easier. Feed twice daily in small amounts. A standing colony of wingless fruit flies is the single best long-term feeding solution and what most experienced clown killi keepers eventually settle on.

Compatibility

• Strictly a surface fish, with the entire activity zone in the top centimetre or two of the water column. Adult body is about 3 to 3.5 cm, occasionally a bit larger; tankmate selection is limited to other nano species
• Best companions live in different zones: pygmy or dwarf corys on the substrate, ember tetras or chili rasboras in the midwater, otocinclus on hardscape, dwarf shrimp on plants. The bottom-and-mid stays busy without anyone competing at the surface
• Other surface-feeding species (hatchetfish, paradise fish, gourami varieties) are bad pairings because they push clown killis off the feeding zone and can outcompete them at meals
• Males display constantly to each other when females are present. In a 20 to 30 litre tank, one male and two or three females is the sensible ratio. Larger tanks with dense floating cover and sightline breaks can hold multiple males
• Snails and shrimp coexist fine with adult killis but eat the eggs, so they need to come out of any tank intended for breeding

Origin and habitat

A miniature surface-dwelling killifish from coastal West Africa. The species is widely distributed across the coastal lowlands of southern Guinea, Sierra Leone, and northwestern Liberia (around Monrovia), in shallow lowland swamps, slow-moving streams, and small rivers, where it lives among marginal vegetation and floating plants in tannin-stained water under heavy forest cover. Some populations occur in slightly saline coastal water, although the species is generally a soft-water blackwater fish. The Belgian naturalist George Albert Boulenger described the species in 1915 as Haplochilus annulatus in 'Descriptions of new freshwater fishes from Sierra Leone' (Annals and Magazine of Natural History, Series 8, 15(86):202-204), with the type locality given as 'Matea, Sierra Leone'; this is now believed to refer to the settlement called Maka in the Moka river system in southern Sierra Leone. The species sits in the family Nothobranchiidae (order Cyprinodontiformes), part of the African rivuline group. The genus name Epiplatys combines Greek epi (above, on top of) with platys (flat, broad), referring to the flattened dorsal surface across the anterior half of the body; the species epithet derives from Latin annulus (ring), after the four bold transverse bars that run between the snout and the caudal fin. The fish was for a long time placed in the monotypic genus Pseudepiplatys, but that arrangement is no longer considered valid because it renders the remaining Epiplatys species paraphyletic; some authors and trade sources still use Pseudepiplatys annulatus, and the question hasn't been universally settled. Synonyms include Haplochilus annulatus, Aplocheilus annulatus, Panchax annulatus, and Pseudepiplatys annulatus. The common name 'killifish' has nothing to do with killing and comes from the Dutch kil, a small creek or ditch. Despite a name that sounds like it should mean 'annual', the species is non-annual: it lives year-on-year like most aquarium fish rather than going through the seasonal die-off cycle of Nothobranchius and other true annual killifish. Adult size is roughly 30 to 35 mm, with the largest recorded specimens approaching 50 mm SL (Romand 1992 key). Males are larger, more colourful, with extended dorsal, anal, and caudal fins; the caudal fin in display carries a flame-like pattern of red, blue, yellow, and orange. Females have shorter, paler, often colourless fins. Colour pattern varies between populations (the anal fin may or may not have a red distal margin; some populations carry yellow dorsal and anal fins). Hobbyists label fish by collection point (Brama Town, Conakry, Fallaba, Fandie, Kasewe, Kinkon, Kobora, Maboshi, Maka, Monrovia, Robertsport, and others) to keep regional bloodlines distinct. IUCN Least Concern.

Breeding

A continuous spawner that lays a small number of eggs each day rather than producing one large clutch. Eggs are tiny, transparent, and attached by short threads to the roots of floating plants (salvinia, water lettuce, water sprite, frogbit), to spawning mops, or to clumps of moss. Adults will eat eggs and fry whenever they find them, and crucially so will any larger snails or shrimp in the tank; Records note specifically that invertebrate tank cleaners should be excluded from a breeding setup because they will consume the eggs. Two approaches work. In a species-only tank with thick floating cover, fry appear spontaneously every few weeks and grow up alongside the parents; this is the lowest-effort method but produces fewer survivors. For directed production, place a conditioned trio (one male and two females) in a small breeding container with a clump of moss or several yarn mops, leave them in for a few days, then move the mops to a hatching container. Eggs are tough enough to be handled by hand. Incubation runs roughly 9 to 14 days at typical aquarium temperatures (quotes 9-12 days; closer to 11). Some breeders pull individual eggs and incubate them on damp peat moss for about two weeks, then add them all to water at once so the fry hatch within the hour as a single age cohort. Fry are tiny but take baby brine shrimp from day one along with microworms or vinegar eels, which is unusually easy for a fish this small.

Common problems

Jumping is the most common single cause of death. The species lives at the surface, is twitchy, and will go through any gap in the tank lid, including the cutouts for filter tubing. A glass top with the openings actually filled (not just covered) is mandatory; floating plants alone aren't a substitute. Water-quality sensitivity is the next issue. Clown killis are often housed in nano tanks of 20 litres or less, which makes ammonia spikes from overfeeding or a single dead snail far more dangerous than in a larger volume; smaller, more frequent water changes (about 10 to 15 percent every few days) work better than one large weekly change. The species cannot tolerate strong current and needs a gentle sponge filter or a heavily baffled output. Feeding fish that won't take dry food is the persistent background problem: without a regular supply of live or frozen food, individuals quietly waste away even though dry flake is in the tank. Internal parasites are reasonably common in wild-caught stock and present as slow loss of condition; levamisole or fenbendazole are the standard treatments. Male-male territorial sparring at the surface is mostly display rather than damage; the fish lack the size and aggression to harm each other meaningfully.

Bioload

Further reading

• Keeping shrimp with fish: what actually works