Taxonomy & naming
Plataplochilus eliasi was described by Walsh, de Bragança, and van der Zee in 2022 in the Journal of Natural History (vol. 55, no. 45–46, pp. 2849–2867). The type locality is the Bondo River, upper Noumbi River basin, Republic of the Congo. As the authority names appear in a publication after the original description by Poll (1952) for the genus, the parentheses in the authority string reflect the subsequent placement in Plataplochilus; the valid combination is recorded in Eschmeyer's Catalog of Fishes.
The genus Plataplochilus belongs to the family Procatopodidae (subfamily Procatopodinae), the African lampeye killifishes — the most basal lineage within the procatopodid radiation. Plataplochilus species are distributed in Central and West Africa, inhabiting forested and savanna stream systems. The family is united by the iridescent light-organ patch situated above the eye, which gives the group its common name.
The specific epithet honours an individual named Elias; the precise etymology is given in the original description but the name follows the standard practice of honouring a collector or benefactor in a patronym.
Morphology
FishBase records a maximum standard length of 1.5 in for males and 1.5 in for females — a typical size for the genus and consistent with the small, slender body plan of procatopodid lampeyes. The body is laterally compressed and elongate, with the dorsal fin inserted well behind the mid-point of the body, a pattern characteristic of the family.
Male colouration is distinctly patterned: the flank above the mid-longitudinal line is olive-green, while the lower half is bright dark blue. A large, round opercular spot and a broad submarginal black band are conspicuous. The iridescent blue-green lampeye patch above the eye is present as in all procatopodids. Females are presumably less colourful, as is typical for the genus, though detailed descriptions of female colouration are not provided in the published literature available.
The combination of the opercular spot and the sharp blue-olive contrast on the flank makes P. eliasi readily distinguishable from congeners, and this colour pattern was among the primary diagnostic characters used by Walsh and colleagues in the original species description.
Habitat
FishBase describes the habitat of Plataplochilus eliasi as very shallow, clear-water creeks over boulders, cobbles, and pebbles with Anubias sp. and overhanging riparian vegetation. The species shows a clear preference for fast-flowing sections of streams on steep slopes — an unusual microhabitat preference within the African lampeye group, which more typically inhabits slow, vegetated margins and swamp edges.
The known range is confined to the Bondo River catchment, a tributary of the Noumbi River basin in the Republic of the Congo. The combination of fast current, coarse rocky substrate, and clear water indicates an upland or hilly-terrain stream rather than a coastal lowland swamp — a habitat that is naturally limited in extent and therefore contributes to the species' restricted known distribution.
Water chemistry in such clear, fast-flowing Central African forest streams is generally soft to moderately hard, with pH in the neutral to slightly acidic range. Genus-level data indicate Plataplochilus species favour pH 6.5–7.5 and well-oxygenated water; the fast-flowing nature of the Bondo River habitat implies good oxygenation throughout.
Feeding
No specific dietary study of Plataplochilus eliasi has been published. Based on the ecology of the genus and the procatopodid family broadly, wild individuals are presumed to be generalist micro-predators, feeding on small aquatic invertebrates, insect larvae, and surface-fallen insects — a diet typical of small stream-dwelling killifishes. The fast-flowing, rocky-substrate habitat suggests drift invertebrates may be an important food source.
In captivity, lampeyes of this group accept small live and frozen foods readily — Daphnia, Artemia nauplii, microworms, and finely chopped bloodworm. Like most small killifishes, P. eliasi will also take high-quality micro-pellets and granules once acclimatised. Varied feeding with appropriately sized items maintains condition and colour in males.
Mating
Plataplochilus eliasi is a non-annual lampeye killifish — a continuous, plant-spawning egg-layer of permanent-water habitats. It does not undergo embryonic diapause and its eggs do not require a dry period to complete development, distinguishing it fundamentally from the annual killifishes of seasonal pools and floodplains.
As with other Plataplochilus species and procatopodids generally, mating involves pairs or small groups moving through fine-leaved vegetation or root tangles, depositing small numbers of adhesive eggs at a time. The eggs are attached individually or in small clusters to plant leaves, fine roots, or other submerged surfaces. Spawning is a protracted, low-intensity process spread over days or weeks rather than a concentrated seasonal event.
Male colouration — particularly the bright blue lower flank and round opercular spot — is almost certainly involved in mate attraction and male–male signalling; the lampeye patch itself may play a role in conspecific recognition in the low-light conditions of forest stream margins.
Breeding
Eggs are adhesive and are deposited among fine vegetation, Anubias leaves, or submerged root masses, consistent with the plant-spawning mode documented for the genus. Incubation period data specific to P. eliasi are not available in the published literature; for Plataplochilus species generally, eggs hatch within one to two weeks at tropical temperatures. Fry are small at hatching but free-swimming and able to take infusoria or commercial micro-foods immediately.
In captivity, a small planted aquarium with clumps of fine-leaved plants (Java moss, hornwort) or spawning mops provides adequate breeding media. Because adults do not actively predate their own eggs with the intensity of some killifishes, small groups can be maintained together in a well-planted tank and eggs collected periodically. Alternatively, a pair can be conditioned separately on live foods and introduced to a breeding tank for a set period before removal.
Growth is relatively rapid for a small killifish; juveniles should reach sexual maturity within a few months under good conditions. The continuous spawning mode means that rearing successive small batches of fry is the most practical approach for hobbyist propagation.
In the aquarium
Plataplochilus eliasi is a rarely encountered species in the hobby given its recent description (2022) and restricted known range; it is not yet established in the ornamental trade to any significant degree. Where maintained, it would suit a small, well-filtered aquarium of 10–15 US gal with clear, well-oxygenated water and a gentle current that reflects the fast-flowing creek habitat. Dense plantings of fine-leaved vegetation alongside open swimming space at mid-water would replicate the natural environment.
Water parameters should target the neutral-to-slightly-acidic range (pH 6.5–7.5) at tropical temperatures consistent with Central African highland streams — approximately 72–79 °F. Because the natural habitat is clear and well-oxygenated, water quality must be maintained carefully; lampeyes are sensitive to ammonia and nitrite accumulation. A tightly fitted lid is advisable, as small killifishes are accomplished jumpers.
The species is peaceful and well-suited to a species tank or a community with other small, non-aggressive fishes of similar size. Males display actively to one another and a small group with more females than males reduces aggression. The striking male colouration — particularly under good lighting — makes P. eliasi a rewarding subject for the specialist killifish keeper.
Conservation
Plataplochilus eliasi has not been assessed by the IUCN Red List; it carries a status of Not Evaluated (NE), reflecting in part how recently it was described — the original paper appeared in 2022. The restricted known range in the Bondo River catchment of the upper Noumbi River basin represents a geographically limited distribution that warrants monitoring.
The preferred habitat — fast-flowing, clear, rocky-substrate streams in forested terrain — is intrinsically vulnerable to the deforestation and agricultural land-conversion affecting Congo Basin watersheds. Forest clearance near headwater streams can rapidly alter flow regimes, increase sedimentation, raise water temperatures, and degrade the clear-water, high-oxygen conditions this species requires. Given the small geographic footprint of the known population, any significant degradation of the Bondo River system could have disproportionate conservation consequences.
Formal assessment by the IUCN and targeted survey work to establish whether the Bondo River population is the species' full range or whether additional populations exist in adjacent drainages would be the most valuable near-term conservation actions. The species' restricted habitat preference and limited known distribution place it in a category where precautionary attention is justified even before a formal Red List assessment is completed.