Taxonomy & naming
Epiplatys zenkeri was first described by Ernst Ahl in 1928 as Panchax zenkeri, with the type locality given as Bipindi, in the Kienke River drainage of southeastern Cameroon. Myers transferred the species to the genus Epiplatys in 1933. Subsequent taxonomy has been contentious: Wildekamp treated zenkeri as a junior synonym of E. grahami (Boulenger, 1911), while Huber recognised it at subspecific rank as E. infrafasciatus zenkeri. FishBase currently follows the synonymy with E. grahami, but Catalog of Fishes (Eschmeyer, Fricke & van der Laan) lists Epiplatys zenkeri (Ahl, 1928) as the valid combination, and that treatment governs the name used here.
The species belongs to the large and taxonomically difficult E. infrafasciatus species group within Epiplatys, a genus of West and Central African surface-dwelling killifishes in the family Nothobranchiidae. Multiple named populations and an aff. form (E. aff. zenkeri from near Édéa) have been documented by killifish workers, reflecting the considerable geographic colour variation across its restricted range. AKA records indicate the species has appeared in the Journal of the American Killifish Association at least three times (volumes 43, 48, and 55), attesting to sustained hobbyist interest in sorting its populations.
Morphology
Epiplatys zenkeri is a slender, somewhat laterally compressed fish reaching approximately 3 in total length in males; FishBase records a maximum of 3 in TL for the species under its E. grahami synonymy, while AKA sources give 3 in standard length for males. The body plan is typical of the panchax group: a slightly flattened dorsal profile suited to hunting at the water surface, an upturned mouth, and a rounded or slightly pointed snout.
The key diagnostic feature distinguishing E. zenkeri from the closely related E. infrafasciatus infrafasciatus is the anal fin, which in zenkeri is solidly orange without the dark marginal bar present in the nominate subspecies. Body colouration is variable between geographic populations — Makondou, Bidjouka, Kribi, and Makouré material differ in the intensity and patterning of flank markings — and this variability underlies much of the historical taxonomic confusion. Males are more vividly coloured than females, a pattern consistent throughout the genus.
Habitat
Epiplatys zenkeri is a fish of the coastal lowland forest zone of southern Cameroon, recorded between the towns of Kribi and Bipindi in the Kienke River drainage. It inhabits swamps and the swampy, slow-moving margins of small forest streams — shaded, heavily vegetated environments where dense riparian vegetation and surface leaf litter are characteristic. These habitats lie within the Cameroonian Highlands forests and associated coastal lowlands, where the Congo Basin meets the Gulf of Guinea.
Water chemistry data from AKA records the natural habitat at pH 6.9–7.1 and hardness of 2–6 °dH — conditions that are near-neutral and very soft, consistent with the dilute, brownish water typical of small coastal forest streams in this part of Central Africa. Temperature in the Cameroonian coastal forest zone is inferred in the range of 73–82 °F. The species is not a seasonal-pond dweller; it occupies permanent or near-permanent water bodies and is not subject to the wet-dry cycle that drives annual killifish life histories.
Feeding
Like other Epiplatys, E. zenkeri is a surface-oriented predator that takes small invertebrates from the water surface and from the upper water column. In its natural swamp and forest-stream habitat the diet is presumed to consist primarily of terrestrial and aquatic insects, small aquatic crustaceans, and other invertebrates that fall onto or congregate near the water surface.
In the aquarium the species readily accepts live and frozen invertebrate foods — small live insects, Drosophila flies offered at the surface, bloodworm, mosquito larvae, and Artemia are all reported as eagerly taken. Dried foods may be accepted by established individuals but live or frozen prey better reflects the species' natural feeding mode and supports condition and colour in both sexes.
Mating
Epiplatys zenkeri is a non-annual killifish whose reproductive strategy is built around plant-spawning rather than soil-deposition. In the wild, pairs or a male attending one or more females court near the water surface or among emergent and floating vegetation, with the male displaying his coloured fins to the female. The species lays adhesive eggs on fine-leaved aquatic plants, floating plant roots, or spawning mops placed at or just below the surface — the clutch is distributed across multiple spawning events over days or weeks rather than deposited in a single episode.
Geographic population differences documented by hobbyists suggest variability in willingness to spawn and in egg production across collection codes; AKA notes describe historically variable egg production by population, a pattern sometimes seen in Epiplatys where fine-scale genetic differentiation between catchments affects reproductive behaviour in captivity.
Breeding
Eggs are adhesive and small, deposited individually or in small numbers on plant material or mop fibres near the surface. Incubation in water at 75–79 °F takes approximately 12–16 days, after which the fry hatch as free-swimming miniatures that are immediately able to take suitably small live foods such as freshly hatched Artemia nauplii or microworms. No diapause period is required — this is a water-incubation species, and eggs can be left on the mops and checked daily, or removed to a separate container to prevent the adults from consuming them.
AKA records describe the species as historically difficult to maintain and breed consistently in captivity. Egg production varies between geographic populations, and some are considerably more productive than others. Water quality and chemistry stability appear important: the near-neutral, very soft conditions of the natural habitat (pH 6.9–7.1, 2–6 °dH) should be replicated as closely as possible for reliable spawning. The fry are relatively large compared to annual-killi fry and grow reasonably quickly when fed well on live foods.
In the aquarium
Epiplatys zenkeri is a specialist fish suited to the dedicated killifish keeper rather than the general community aquarium. FishBase flags the species as difficult to maintain in captivity — a rating consistent with the AKA literature on its variable breeding success. A pair or small group can be kept in a modest-sized, tightly lidded aquarium of 10–15 US gal; the tight lid is essential, as all panchax are strong jumpers.
Water chemistry should reflect the natural soft, near-neutral conditions: pH 6.8–7.2 and hardness under 6 °dH where possible, temperature 73–79 °F. Subdued lighting, dark substrate, and abundant floating plant cover (Indian fern, Java moss, or fine-leaved stem plants) recreate the forest-stream aesthetic and encourage natural behaviour. The species is placid toward similarly sized fish but may prey on very small tankmates; it is most successfully kept in a species setup or alongside comparably sized, non-aggressive fish.
Hobbyist populations are maintained almost exclusively by collection-code: Makondou, Bidjouka, Kribi, and Makouré are among the known population labels, and killifish societies (AKA and its European counterparts) are the primary source of captive stock. Given the restricted natural range, captive maintenance of individual populations is of conservation significance.
Conservation
The IUCN Red List currently assesses Epiplatys zenkeri as Data Deficient (DD). FishBase has separately carried a Least Concern (LC) assessment dated 4 June 2019 under the species' synonymy with E. grahami, but that reflects the broader distributional picture of the combined taxon rather than a species-specific finding for E. zenkeri. The Data Deficient rating instead reflects the taxonomic uncertainty here: if E. zenkeri is treated as distinct, with a native range restricted to the corridor between Kribi and Bipindi in coastal Cameroon, there is not yet enough population- and range-specific data on that narrower taxon to support a confident category.
The Kienke River drainage and the surrounding coastal forest of southern Cameroon face ongoing pressure from logging, agricultural expansion, and road development. Small-stream and swamp habitats in this region can be dramatically altered by canopy removal, which raises water temperatures, increases sedimentation, and reduces the leaf-litter inputs that support the invertebrate prey base for surface predators like Epiplatys. The narrow documented range of E. zenkeri means that any localised habitat degradation could disproportionately affect the population, even though the data available are currently insufficient to assign a specific threat category. The killifish hobby's practice of maintaining geographically coded populations provides an informal ex situ insurance against local extirpation.