Taxonomy & naming
Plataplochilus mimus was described by Poll and Lambert in 1965, with the type locality recorded as N'Koltang, at PK 28 (the 28th kilometre marker) along the road between Libreville and Kango in Gabon. Some secondary sources list the authority as Lambert, 1967, but the valid combination accepted by Eschmeyer's Catalog of Fishes (CAS) is Plataplochilus mimus (Poll & Lambert, 1965), with the parenthetical authority indicating the name has been transferred since the original description.
The genus Plataplochilus belongs to the family Procatopodidae — the African lampeyes — within the order Cyprinodontiformes. It is one of nine currently recognised species in the genus, a moderately small West and Central African radiation. The lampeyes as a group are sometimes treated as a subfamily Procatopodinae within a broader Aplocheilidae sensu lato, but modern molecular phylogenies consistently support Procatopodidae as a separate family. The genus name Plataplochilus combines the Greek platus (flat, broad) with aplocheilos (without a lip groove) — a structural reference to oral anatomy, though the precise original intent of the combination is not elaborated in most sources.
The specific epithet mimus is Latin for 'mimic' or 'imitator', suggesting the species resembles another taxon, though the basis for the name is not documented in the available literature.
Morphology
Plataplochilus mimus is a diminutive fish, reaching a maximum recorded standard length of 1 in according to FishBase — placing it among the smallest members of an already small genus. The body plan is typical of the procatopodid lampeyes: a slender, slightly laterally compressed form with a subterminal mouth angled upward, an iridescent reflective patch (the light organ) positioned above and just behind the eye, and a pattern of metallic blue-green iridescence along the flanks. This supraocular iridescence is the hallmark of the lampeye group and is produced by guanine-based reflective cells.
Sexual dimorphism is present, as in most killifish. Males are more vividly coloured, displaying the full extent of the blue-green lateral sheen and more defined fin coloration; females are plainer and fuller-bodied when gravid. The closely related genus Procatopus shares very similar structural features with Plataplochilus, and the two groups were historically confused — detailed descriptions from the original literature are necessary to distinguish them reliably in the field or in the aquarium.
Habitat
The known distribution of Plataplochilus mimus encompasses Gabon and Equatorial Guinea, in the lowland rainforest zone of west-central Africa. The type locality, N'Koltang on the Libreville-Kango road in Gabon, lies in the coastal lowlands where small clear-water streams and forest pools are abundant. Related Procatopodidae typically occupy small rivers of less than ten metres width and less than one metre depth during the dry season — clear, well-oxygenated permanent water with a mix of submerged roots, leaf litter, and rocky or woody structure.
Water chemistry for the West African forest lampeyes tends toward the slightly acidic: pH values around 6.0 have been recorded for similar habitats, and temperatures in the humid forest zone remain warm year-round, generally above 75 °F and consistent with the figures of over 81 °F (80 °F) cited for closely related Procatopus. These are permanent, non-seasonal water bodies — not temporary pools that dry out annually — which is the fundamental ecological basis for the non-annual reproductive strategy of the group.
Feeding
No species-specific dietary data for Plataplochilus mimus appears in the available literature. By analogy with other small procatopodid lampeyes occupying similar forest-stream habitats, the diet is presumed to consist primarily of small invertebrates — microcrustaceans, aquatic insect larvae, and similar zooplankton — taken from the water column and near the surface. The upturned mouth is consistent with a surface or mid-water feeding posture.
In the aquarium, closely related lampeyes are reported to accept small live and frozen invertebrates (Artemia nauplii, Daphnia, micro-worms) as well as appropriately sized dried foods. The small adult size of P. mimus constrains the particle size of acceptable prey; fine-grade foods are necessary throughout life.
Mating
Plataplochilus mimus is a non-annual lampeye killifish that reproduces continuously in permanent water, without any diapause stage in the egg. Lampeyes of this kind do not produce drought-resistant eggs capable of surviving substrate desiccation; instead they spawn repeatedly over an extended season, producing small numbers of adhesive eggs at each spawning event. The genus Plataplochilus, together with the closely allied Procatopus, is classified among the Leuchtaugen-Spaltenlaicher (lampeyes that attach eggs in crevices) — a category in the German killifish literature that refers specifically to species placing eggs in rock or wood crevices rather than wrapping them around fine plant leaves or depositing them in open water.
Males court females with lateral displays that maximise the visibility of the iridescent flank sheen and the light organ above the eye. Spawning is a brief contact event resulting in one or a few eggs being deposited and fertilised; the pair then separates and may repeat the process multiple times per day over an extended period.
Breeding
Fertilised eggs of Plataplochilus mimus and related crevice-spawning lampeyes are adhesive and are placed by the female, often aided by the male, into a sheltered crack, gap between rocks, or piece of submerged wood. No diapause occurs: incubation proceeds in water at ambient temperature and is relatively short — for closely related Procatopus, a two-week water-incubation period has been documented. Hatchlings are small but free-swimming and comparatively well-developed relative to annual killies that produce diapausing eggs.
In the aquarium, breeding can be encouraged by providing fine-leaved moss or artificial crevice spawning sites (small clay tubes, bundles of peat fibre, or narrow-gap rock arrangements). Eggs should be collected regularly or the adults separated from the spawning medium, as adult lampeyes may consume eggs if left in close contact. Fry can be raised on infusoria and freshly hatched Artemia nauplii from first feeding, progressing to finely ground prepared foods as they grow.
In the aquarium
Plataplochilus mimus is a specialist fish rarely seen in the mainstream hobby but known to dedicated killifish enthusiasts, particularly through organisations such as the American Killifish Association which maintains a species registry for the genus. Its minute adult size (under 1 in SL) and the delicacy attributed to closely related lampeyes — Procatopus and allies are described in the hobbyist literature as 'extremely fragile' — make it a fish for experienced keepers rather than beginners.
A small, well-filtered and well-oxygenated aquarium with tight-fitting lids is recommended, as with all killifish. Water should be slightly acidic to neutral (pH 5.8–6.8), soft to moderately hard, and maintained at 75–81 °F to reflect the West African forest-stream environment. The species is best kept as a small group of males and females; males are generally not aggressive toward one another at the small group scale typical for a species of this size. Tankmates, if any, should be comparably sized and non-predatory. Because it attaches eggs in crevices rather than spawning over mops, standard killifish mop-breeding setups will not be effective; dedicated crevice spawning media are needed for successful reproduction.
Conservation
Plataplochilus mimus is assessed as Not Evaluated (NE) by the IUCN Red List, meaning it has not yet been the subject of a formal conservation assessment. This status reflects the relatively limited attention that small, range-restricted African lampeyes have received from the broader conservation community rather than any confirmed absence of threat.
The species is known from the lowland rainforest of Gabon and Equatorial Guinea — a region where primary forest cover remains substantial but faces ongoing pressure from logging, oil extraction, and agricultural expansion, particularly near the coastal lowlands where the type locality lies. Small-bodied killifish occupying narrow geographic ranges in specific stream habitats are inherently vulnerable to watershed disturbance; the clearing of riparian forest changes water temperature, sedimentation, and flow regimes in ways that can eliminate populations from individual streams. A formal assessment under IUCN criteria would require field surveys to document the actual range, population structure, and local habitat condition of P. mimus — work that has not been published in the sources available.