Taxonomy & naming
Epiplatys njalaensis was described by Neumann in 1976, with the type locality in Sierra Leone. The Catalog of Fishes (Fricke, Eschmeyer & Fong, CAS) records the valid combination as Epiplatys njalaensis Neumann, 1976 within the family Nothobranchiidae, the African rivulines — the family that encompasses virtually all African annual and non-annual killifishes.
The genus Epiplatys Gill, 1862 is a large and species-rich assemblage of surface-oriented West and Central African panchaxes. Within it, njalaensis is placed in the Fasciolatus species group, a cluster of banded, predominantly forest-zone species. Hobbyists acquainted with the genus sometimes note that njalaensis is the smallest member of this group, at 2.5 in TL. The name Epiplatys is often glossed as referring to the flattened, surface-skimming body profile; njalaensis is a toponym derived from Njala, the agricultural research station and university town on the Taia River in southern Sierra Leone — a region that served as a collection point for early ichthyological surveys of the country's forest streams.
Morphology
Adults reach a maximum of 2.5 in total length, making njalaensis one of the more modestly sized members of Epiplatys. The body plan is slender and somewhat dorsoventrally flattened, with the dorsal profile nearly straight and the mouth terminal and upturned — adaptations shared across the panchax grade for hunting prey at or just below the water surface.
The most immediately recognisable feature is the pattern of ten to twelve diagonal, dark vertical-to-oblique bands running across the flanks on a body ground colour that hobbyists describe as blue-tinted or blue-bodied. The caudal fin departs from strict symmetry, with the fin rays extending slightly off-centre — a character noted by killifish specialists. Sexual dimorphism is present: males are more vividly coloured with bolder banding and the more pronounced caudal extension, while females are plainer and become noticeably deeper-bodied when gravid.
Habitat
Epiplatys njalaensis is recorded from Sierra Leone and Guinea, where it inhabits small rivers and forest brooks under closed-canopy cover. The species is benthopelagic in the broad sense — present through the water column of shallow, shaded streams — and is non-migratory within its forest-stream habitat. FishBase records the thermal range as 72–82 °F, consistent with the relatively stable temperatures that persist inside intact West African rainforest.
Collections from killifish clubs reference multiple specific localities in Sierra Leone, including sites near Freetown (Freetown-Halbinse) and interior stations such as Rowari (SL-93-19) and Fadugu (SL-93-36). These locality codes indicate that the species has been documented across a range of elevations and forest zones within the country. Broadly speaking, the spawning-ground preference for plants and surface cover places njalaensis in the upper water column of shaded, vegetation-rich reaches rather than in open, sun-exposed water.
Feeding
In common with other surface-oriented Epiplatys, E. njalaensis is a carnivore feeding primarily on small invertebrates — aquatic and terrestrial insects, larvae, small crustaceans, and zooplankton encountered at or near the water surface. The upturned mouth positions the fish well to take floating or near-surface prey.
In captivity the species is straightforward to feed on live and frozen foods: Drosophila fruit flies and other small flying insects, small live or frozen Artemia, Daphnia, bloodworm, and tubifex. The relatively small adult size means that food items must be appropriately sized; large pellets or chunks are refused. A varied diet of small live and frozen invertebrate foods maintains colour and condition in captive fish.
Mating
Epiplatys njalaensis is a non-annual, plant-spawning killifish. Unlike the West African annual species that bury drought-resistant eggs in pond sediment, njalaensis spawns continuously or intermittently throughout the year in its permanent forest-stream habitat. Pairs scatter adhesive eggs individually among fine-leaved aquatic plants, floating mosses, or other vegetation near the surface; the eggs adhere to plant material and are abandoned by the parents after deposition.
In the aquarium, spawning behaviour is readily induced by providing dense clumps of fine-leaved plants or commercial spawning mops. The American Killifish Association notes that the species responds well to slightly alkaline conditions for breeding, with water pH above 7 reportedly conducive to spawning success. The pair approach the spawning site together, a brief embrace occurs alongside the plant or mop, and one or a small number of eggs is released per visit; spawning continues over days to weeks rather than in a single mass-release event.
Breeding
Eggs are relatively large for the body size, adhesive, and incubated fully in water with no diapause phase. Incubation period in warm water is typically two to three weeks, after which fry hatch as miniature replicas of the adults and are immediately free-swimming. First foods for the fry are appropriately small: infusoria, vinegar eelworms, or very fine commercial fry powder in the earliest days, graduating quickly to newly hatched Artemia nauplii as the fry grow.
Hobbyists report that E. njalaensis is reasonably easy to breed in a small, dedicated spawning tank. Eggs can be collected from the mop every few days and incubated separately in a shallow container of clean water, which reduces the risk of fungus and prevents older, faster-growing fry from outcompeting or eating later-hatching siblings. Fry grow steadily and reach sexual maturity within a few months. The Arizona Rivulin Keepers characterise the species as easy to breed — a contrast to some of its close relatives in the Fasciolatus group, which can be more demanding.
In the aquarium
Epiplatys njalaensis is suited to a small, well-planted species or species-group aquarium. A tank of 10–15 US gal with a tight-fitting lid (mandatory for surface-skimming killifishes that jump readily), gentle filtration, and dense plantings of fine-leaved vegetation at or near the surface replicates the shaded forest-stream environment and provides the spawning substrate the fish require. Floating plants are particularly useful, both as cover and as natural spawning sites.
FishBase notes that the species can be difficult to maintain, suggesting it is more sensitive than the entry-level Epiplatys (such as E. dageti) in some respects — likely a reflection of its preference for cool, clean, softly flowing forest-stream water rather than the warmer, more stagnant conditions tolerated by savanna panchaxes. The recommended temperature range of 72–82 °F and a pH at or slightly above neutral aligns with the chemistry of well-oxygenated forest brooks. Hard, warm, or poorly filtered water should be avoided.
In a community context the species is best kept with small, peaceful tankmates of comparable size, or kept purely as a species display. Its own conspecifics can be kept in groups, with one male to two or more females to distribute any spawning-associated chasing. The brilliant banding and blue body colouration of males in good condition make for an attractive display.
Conservation
The IUCN Red List assessment conducted by Diallo in 2020 placed Epiplatys njalaensis in the Near Threatened (NT) category. Sierra Leone has experienced extensive forest loss over recent decades: primary forest cover has been drastically reduced by agricultural expansion, charcoal production, and artisanal mining, and the small forest streams that njalaensis depends on are increasingly fragmented, silted, and exposed to direct sunlight as riparian tree cover is removed. Guinea, where the species also occurs, faces similar pressures across its forest zones.
Near Threatened is the step below Vulnerable on the IUCN threat scale, indicating that the species approaches the quantitative thresholds for Vulnerable status and is monitored with concern. The principal threats are habitat degradation and the reduction in area and connectivity of intact forest-stream networks, rather than targeted exploitation. Because the species appears to depend on shaded, high-quality stream conditions, it is more vulnerable to deforestation than more tolerant lowland or savanna killifishes. No captive conservation programme for this species is formally documented, but the interest of specialist killifish clubs in collecting and maintaining location-coded strains provides an informal assurance against total loss from the hobby.