Taxonomy & naming
Epiplatys duboisi was described by the Belgian ichthyologist Max Poll in 1952, in 'Notes sur les Cyprinodontidae de Léopoldville avec description d'une espèce nouvelle du genre Epiplatys' (Revue de Zoologie et de Botanique Africaines 46 (3–4): 295–300), from material collected near N'dolo in what is now Kinshasa, on Pool Malebo — the lake-like widening of the Congo River then known as Stanley Pool. The holotype (MRAC 80139) is held at the Royal Museum for Central Africa, Tervuren.
The generic placement has moved back and forth. Radda (1980) briefly listed the species in Aplocheilus; Wildekamp and co-authors (1986), followed by much of the killifish literature since, separated it into the monotypic genus Aphyoplatys, and the combination Aphyoplatys duboisi remains widespread in hobby sources and is the name under which the IUCN assessment was compiled. More recent treatments — Lazara (2001), Collier et al. (2009), and Huber (2024) — return the species to Epiplatys, and Eschmeyer's Catalog of Fishes currently records the valid name as Epiplatys duboisi Poll, 1952, written without parentheses because the fish stands once more in its original genus. That name is followed here, with Aphyoplatys duboisi treated as the historical combination.
The genus name Epiplatys combines the Greek epi (upon, at the surface) and platys (flat, broad), alluding to the flattened head and the habit of holding station at or just below the water surface — a characteristic posture shared across the panchax group. The specific epithet duboisi commemorates a collector or scientist named Dubois associated with Poll's Congo material.
Morphology
Epiplatys duboisi is a small, slender killifish with a maximum total length of 1.5 in (FishBase); some field and aquarium reports note individuals barely reaching 1 in — firmly nano-fish territory. The body plan is typical of surface-adapted panchax: the dorsal profile is relatively flat and the head slightly flattened on top, positioning the upward-angled, terminal to slightly supraterminal mouth for taking prey from or just below the water film. The dorsal fin is set far back, above or just behind the anal-fin origin.
Colouration in males is subdued but intricate: a warm golden-brown to olive base overlaid with small red-orange dots or dashes in horizontal rows along the flanks — a finely spotted, ladder-like pattern under good light — with reddish or orange edging on the fins of breeding males (Aquarium Glaser; AKA reference library). Females are more cryptic: plainer brownish-olive, with reduced patterning and a noticeably rounder body when carrying eggs. Sexual dimorphism is therefore present and reliably used to sex fish in the aquarium.
Habitat
The species inhabits the shallow, weedy margins of brooks, small streams, and swamps within lowland rainforest (FishBase). FishBase records the known distribution across Pool Malebo, the lower Kwango, lower Kasai, and middle Congo River in the Democratic Republic of Congo, as well as the Nkéni, Alima, Vouma, Kouyou, and Likouala drainages in the Republic of Congo — a range centred on the Congo Basin and its northern tributaries; Eschmeyer's Catalog of Fishes summarises it as the middle and upper Congo River basin.
Water chemistry in these habitats is moderately soft and slightly acidic to neutral: FishBase gives pH 5.8–7.2 and temperature 72–79 °F, consistent with shaded rainforest streams naturally low in dissolved minerals and buffered by leaf litter and humic compounds. Hobbyist field summaries add texture: collection sites are typically very shallow — around 12 in — over mud and leaf litter, the AKA reference library notes hardness under 50 ppm with field pH at some Congo forest localities dropping well below the FishBase range, and the Killi Club de France documents natural seasonal temperature swings from about 68 °F to above 86 °F. Dense submerged or emergent vegetation is a constant habitat feature. The waters are fresh, and the species is not associated with brackish or seasonally drying environments.
Feeding
Epiplatys duboisi is a micropredator with a strong preference for small invertebrates, consistent with the surface-feeding habit of the panchax group; FishBase records a trophic level of about 3.1, a diet centred on small animal prey. In the wild it takes small insects, insect larvae, zooplankton, and any invertebrate small enough for its diminutive mouth, picking prey from the water surface or just below — the upturned mouth is particularly well adapted to intercepting terrestrial insects fallen onto the surface film.
In captivity the species adapts readily to prepared and cultured foods: Aquarium Glaser and the AKA reference library both confirm that it accepts fine dried foods (micro-pellets, crushed flake) alongside Artemia nauplii, daphnia, grindal worms, and other small live or frozen invertebrates. Live or frozen foods elicit the strongest feeding responses and best support male colour. Small, frequent feedings suit its continuous surface-patrolling behaviour better than single large meals.
Mating
Epiplatys duboisi is a non-annual killifish and a plant spawner — one of the defining biological distinctions within the African killifishes. Unlike annual species whose reproduction is timed to the complete desiccation of seasonal pools, duboisi lives in permanent or near-permanent streams and swamps where water persists year-round, and its reproductive strategy reflects that permanence: spawning is a continuous or near-continuous low-level activity rather than a single explosive event triggered by the return of rains.
Male courtship involves lateral displays, fin-spreading, and colour intensification directed at females. The male manoeuvres alongside or slightly below the female near a patch of fine-leaved vegetation or floating plant roots, then executes a brief spawning embrace in which one or a small number of adhesive eggs are deposited directly onto the plant material. This pattern repeats over days and weeks, distributing eggs across the spawning substrate at various developmental stages simultaneously — a scatter-and-deposit strategy that spreads reproductive risk. There is no nest and no parental care.
Breeding
Eggs are adhesive and remain attached to plant leaves, roots, or spawning-mop fibres, incubating in the water column rather than undergoing diapause in a dry substrate — no dry period is required or tolerated, the diagnostic contrast with annual killifish. The eggs are large for so small a fish, about 0.5 in across, and the Killi Club de France's species sheet gives an incubation of 10–15 days at typical maintenance temperatures, with sexual maturity at roughly eight months and adults relatively long-lived for killifish.
In the aquarium, a dedicated breeding setup with a thicket of fine-leaved plants (Java moss, hornwort) or synthetic spawning mops placed near the surface provides the necessary spawning substrate. Eggs can be picked from the mops every few days and incubated separately in small containers of aged, soft water to prevent predation by the parents. Fry are tiny and need the finest first foods — infusoria, Paramecium, or green water for the first days — before graduating to newly hatched brine shrimp nauplii and other small live foods as they grow. Because spawning is continuous, multiple generations can be maintained simultaneously, making population maintenance straightforward for a committed hobbyist.
In the aquarium
Epiplatys duboisi suits a small, densely planted species aquarium: a tank of 5.5–15 US gal with a tight-fitting lid (surface-dwelling killifishes jump readily), a layer of floating plants to diffuse light and provide cover, and fine-leaved plants or spawning mops near the surface. Water should be maintained at 72–79 °F, pH 5.8–7.2, and low hardness — the AKA reference library recommends under 50 ppm — with Indian almond leaf, alder cones, or peat extract helping replicate the soft, slightly tannin-stained water of its rainforest habitat. Gentle filtration via a sponge filter maintains water quality without the surface turbulence that would disturb a surface-patrolling species from still forest pools.
The species is peaceful toward similarly sized tankmates and can be kept as a pair, a trio, or a small group. Males may show low-level territorial behaviour toward other males but rarely cause injury in a well-planted tank. Its dwarf dimensions put it at risk from any larger or more boisterous tankmate, so a species tank or a community of equally gentle micro-fish with matching water chemistry is the sensible arrangement.
Due to its small size, limited distribution, and moderate rarity in the trade, this fish is kept mainly by specialist killifish hobbyists — often under its older name Aphyoplatys duboisi. The American Killifish Association maintains records and coordinates exchange of stock among members, and sourcing from club fish lists rather than pet stores is the most reliable route to obtaining it.
Conservation
The IUCN Red List assessed this species as Least Concern (LC) — assessed in February 2009 and published in 2010, under the name Aphyoplatys duboisi (assessor T. Moelants) — noting a reasonably broad distribution across the Congo Basin and associated drainages, with no major immediate decline identified at the time. The Congo Basin hosts one of the largest contiguous rainforest blocks remaining on Earth, and the lowland stream habitats this species occupies are still broadly intact across much of its range — a different situation from many West African killifish endemics tied to isolated forest fragments.
Nonetheless, the Congo Basin faces intensifying pressure from industrial logging, small-scale agriculture, and expanding settlement, all of which degrade the shaded, clear-water stream habitats that surface-dwelling panchax require. Sedimentation, increased turbidity, and water-temperature rises associated with canopy removal are the most direct threats to stream killifishes of this type, and the very shallow, stagnant-water microhabitats this species favours are disproportionately affected by catchment disturbance. The assessment is now more than fifteen years old, and the rate of land-use change in the basin has accelerated since; an updated evaluation would be valuable. The species does not appear on the CARES Preservation Program list but warrants attention from the killifish hobby as a fish dependent on the ongoing integrity of Central African rainforest hydrology.