Taxonomy & naming
Epiplatys barmoiensis was described by the Swedish ichthyologist Gustaf Svensson in 1933, with the type locality recorded as Barmoi, in the Western Area of Sierra Leone. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) treats the name as valid within the genus Epiplatys Gill, 1862, which belongs to the family Nothobranchiidae — the African killifishes — as currently recognised following the molecular work that split the old Aplocheilidae into separate New World and Old World families.
The genus Epiplatys is large and diverse, encompassing the panchax group of West and Central African surface-hunting killifish. The name Epiplatys derives from the Greek epi ('upon' or 'above') and platys ('flat' or 'broad'), likely alluding to the flattened dorsal profile and the surface-skimming lifestyle of these fish. The species epithet barmoiensis is a toponym, referring directly to the type locality of Barmoi. No subspecies are currently recognised, and the species has not been subject to recent molecular revision; its precise relationships within the genus remain to be resolved by phylogenetic analysis.
Morphology
Epiplatys barmoiensis reaches a maximum total length of approximately 3 in, placing it among the mid-sized members of the genus. Like all Epiplatys, the body plan is adapted for surface predation: the dorsal profile is nearly flat from the occiput to the dorsal fin origin, the mouth is strongly upturned and terminal to superior in position, and the lower jaw projects slightly beyond the upper. The flanks are laterally compressed toward the caudal peduncle but the anterior body is somewhat rounded in cross-section.
Colouration in males is the typical Epiplatys pattern: an olive-green to brownish-green body with a series of darker transverse bars or spots on the flanks, metallic iridescent scales catching the light, and brightly coloured fins. The caudal fin typically shows yellow-orange to red markings, and the dorsal and anal fins are similarly embellished. Females are more uniformly coloured, shorter-finned, and plainer, lacking the vivid fin pigmentation of males. Sexual dimorphism is therefore straightforward and allows confident sexing of adults in aquarium conditions.
Habitat
The native range of Epiplatys barmoiensis spans a comparatively narrow coastal corridor from southwestern Sierra Leone to southwestern Liberia — the heart of the Upper Guinea biodiversity hotspot, one of Africa's most species-rich and heavily threatened forest zones. Within this range the species occupies coastal plain waters: swampy areas, shallow pools, and small rivers draining to the Atlantic, from virtually static water to moderately fast-flowing streams.
Water chemistry recorded for the species reflects the soft, slightly acidic conditions typical of West African forest streams. FishBase records temperature 75–81 °F, pH 6.3–6.6, and hardness 1–2 dGH. These are clear, soft, low-conductivity waters shaded by riparian and gallery forest, with leaf litter and surface vegetation providing cover. The fish is a surface- and mid-water dweller, remaining in the upper water column and near overhanging vegetation where it hunts terrestrial and aquatic invertebrates that fall or accumulate at the surface. As a non-annual species it lives in permanently watered habitats and does not experience the dry-season desiccation that drives diapause in annual killifish found elsewhere in West Africa.
Feeding
Epiplatys barmoiensis is an opportunistic surface carnivore. In the wild, the strongly upturned mouth and surface-oriented body posture are adaptations for taking insects and other invertebrates from the water surface — fallen terrestrial insects, emerging aquatic larvae, and small crustaceans are the likely primary prey. The fish also takes small aquatic invertebrates from the mid-water column and from vegetation.
In captivity the species accepts a wide range of small live and frozen foods: Drosophila fruit flies and small crickets dropped onto the surface are taken eagerly and replicate the natural feeding mode. Frozen bloodworm, Artemia, and Daphnia are also accepted, as are small pellets and flake foods once the fish are acclimatised. Feeding variety promotes good colouration and condition. Because of the upturned mouth, surface-drifting or slowly sinking foods are preferred over sinking pellets.
Mating
Epiplatys barmoiensis is a non-annual killifish with a plant-spawning reproductive strategy. Pairs form loose bonds and spawn intermittently over extended periods rather than in a single concentrated event, reflecting the stable, permanent water conditions of their native habitat. There is no requirement for a dry season or egg diapause. Courtship is active: males display their fin colours and lateral body bars to females, pursuing and manoeuvring beneath them in preparation for the spawning embrace.
Eggs are deposited adhesively on fine-leaved plants, roots, algal mats, or floating spawning mops near the water surface or among submerged vegetation. Each spawning event produces a small number of eggs, but production is continuous over weeks or months when the fish are in good condition. The male wraps briefly around the female as each egg is fertilised and pressed against the chosen surface. This protracted, low-volume approach contrasts sharply with the mass single-event spawning of annual species.
Breeding
Under aquarium conditions, Epiplatys barmoiensis spawns readily on fine-leaved plants such as Java moss or on commercial floating nylon spawning mops. The British Killifish Association reports that eggs hatch in approximately 12–15 days at 73 °F, with incubation time shortening at higher temperatures within the safe range. Eggs are small and adhesive; they can be left on the mop or plant and inspected periodically, or collected and transferred to a shallow hatching container with a small amount of aquarium water and a fungicide such as methylene blue to reduce losses.
The fry are tiny at hatching and require appropriately small first foods: infusoria, Paramecium, or powdered fry food for the first days, followed by freshly hatched Artemia nauplii and micro-worms as they grow. The fish grow relatively quickly in warm, clean water. Adults do not provide parental care and will consume eggs and small fry if given the opportunity, so either egg collection or separation of fry is advisable. Cleanliness of the water is reported to be important for egg viability and fry survival.
In the aquarium
Epiplatys barmoiensis is kept primarily by specialist killifish hobbyists. FishBase notes that the species is considered difficult to maintain in the aquarium, a characteristic more likely reflecting sensitivity to water quality deterioration and the need for consistently soft, slightly acidic, warm water than any fundamental hardiness problem. A well-maintained species tank with regular partial water changes, soft and slightly acid water matching the wild parameters (pH 6.3–6.6, 75–81 °F, very low hardness), and surface cover in the form of floating plants or vegetation near the waterline suits the species well.
A tight-fitting lid is essential: like most surface-oriented killifish, Epiplatys barmoiensis is an accomplished jumper and will exit an uncovered tank. A species or near-species setup is generally recommended — conspecific males may spar, but injuries in a well-planted aquarium with adequate space are usually minor. The tank should not be heavily stocked with fast-moving, boisterous tankmates that compete at the surface for food. Small West African tetras, Procatopus lampeyes, or peaceful dwarf cichlids from overlapping ranges make compatible companions in a suitably sized aquarium. Live foods offered at the surface provide enrichment and keep the fish in best colour.
Conservation
The IUCN Red List assessment of 2020, carried out by Diallo, Bousso, and Lalèyè, places Epiplatys barmoiensis in the Least Concern (LC) category. The assessment acknowledges that the species occurs across a range of coastal lowland habitats from southwestern Sierra Leone to southwestern Liberia and is not currently considered to face population decline severe enough to qualify for a threatened category.
Nevertheless, the restricted coastal range of the species places it squarely within the Upper Guinea forest hotspot, one of the world's most threatened tropical forest regions. Sierra Leone and Liberia have experienced substantial deforestation over recent decades for agriculture, mining, charcoal production, and logging, with associated siltation, chemical run-off, and alteration of stream hydrology degrading the small, shaded coastal rivers and swampy plains that the species requires. The soft, low-conductivity water chemistry of its habitat makes it sensitive to catchment disturbance. Introduction of exotic species — including the mosquitofish Gambusia affinis, which has spread widely across West Africa as a mosquito control measure — poses an additional local threat. Continued monitoring of the species across its range is warranted given the pace of habitat change in the region.