Taxonomy & naming
Enteromius okae was described by the American ichthyologist Henry Weed Fowler in 1949, originally placed in the broad genus Barbus as Barbus okae. The parenthetical authority — (Fowler, 1949) — in the current valid name reflects that subsequent reclassification has moved the species out of Fowler's original genus. The Catalog of Fishes (Eschmeyer, CAS), the governing authority for valid fish names, records the current valid combination as Enteromius okae (Fowler, 1949).
The genus Enteromius is a large assemblage of small African barbs separated from the formerly catch-all Barbus following molecular phylogenetic and morphological work establishing that the old genus was deeply polyphyletic. The name Enteromius had been available since Cope (1867) and was resurrected to accommodate the African lineage that includes most of the small, two-barbelled cyprinids of sub-Saharan Africa. The specific epithet okae is presumed to reference a locality or river name from the type collection, though detailed description notes are sparse in secondary literature.
Morphology
Enteromius okae is a small barb of the typical slender-to-moderately-deep Enteromius body plan. Specific morphometric data — standard length, fin-ray counts, scale formulae, and colouration — are not well documented in accessible secondary literature, and the primary description by Fowler (1949) remains the principal record. Like most members of the genus, it is presumed to have the two pairs of barbels typical of many Enteromius, a complete lateral line, and the relatively small, silvery to olivaceous body colouration common to West African stream barbs.
Without reliably sourced measurements the maximum recorded size cannot be stated with confidence; many Enteromius of the West African lowland stream fauna reach roughly 2–3 in total length, but a species-specific figure is not available from the sources surveyed.
Habitat
Enteromius okae is a West African endemic. Its native range is associated with river systems in the region of West or West-Central Africa consistent with the name "okae" in the original description, though precise basin-level data are sparse in secondary literature. West African Enteromius typically inhabit lowland rivers, savanna streams, forest gallery streams, and seasonal floodplain waters — generally clear to lightly turbid, warm habitats with moderate flow and substrates of sand, gravel, or leaf litter.
Water chemistry across the West African stream fauna varies considerably, from soft, slightly acidic forest waters to more neutral and moderately hard savanna and floodplain rivers. Without species-specific field data a precise chemistry profile cannot be stated; general West African lowland conditions of roughly 73–82 °F and broadly neutral pH are a reasonable baseline for husbandry purposes.
Feeding
No specific dietary studies of Enteromius okae are on record in the sources consulted. By analogy with its congeners — and with the feeding ecology of small West African cyprinids generally — it is assumed to be an opportunistic omnivore, taking small invertebrates (aquatic insect larvae, microcrustaceans, worms), algae, diatoms, and organic detritus from the substrate and water column.
In aquaria, small omnivorous barbs of this size class are reliably fed on good-quality micro-pellets and flake supplemented with live or frozen foods such as bloodworm, daphnia, and brine shrimp nauplii.
Mating
Enteromius okae is an egg-scattering, non-guarding spawner, consistent with the reproductive mode universal in barbs. No nest is built, no territory is held beyond the immediate courtship chase, and no parental care is given. A conditioned male pursues a gravid female through vegetation or over the substrate, and eggs and milt are released together in brief, pressing contacts.
The adhesive eggs settle among fine-leaved plants, root tangles, or on the substrate surface. Adults typically consume eggs immediately if they remain in the spawning area. No species-specific spawning accounts from the wild or aquarium are available in the literature surveyed.
Breeding
No captive breeding records for Enteromius okae are documented in available aquarium literature; the species is essentially absent from the hobby and no specialist accounts have been traced. General protocol for small West African Enteromius in aquaria follows the standard egg-scatterer method: a shallow, well-planted spawning tank with soft to moderately hard water near the species' native conditions, fine-leaved plants or a spawning mop, and removal of adults after spawning to prevent egg predation.
Eggs of comparably sized Enteromius typically hatch within 24–48 hours at tropical temperatures, with free-swimming larvae requiring infusoria or commercial first foods in the days that follow. Because this species is not in general circulation in the trade, specific data on fecundity, egg size, and larval development remain unrecorded.
In the aquarium
Enteromius okae is not an established aquarium fish and is essentially absent from the international ornamental trade. It has not featured in specialist aquarium literature, and no husbandry accounts have been traced. Should specimens become available, general care principles for small West African stream barbs would apply: a roomy, well-filtered aquarium with warm water (approximately 73–82 °F), a broadly neutral pH, soft to moderately hard water, gentle to moderate flow, and adequate open swimming space alongside some planting or woody cover.
Small schooling barbs of this type are best kept in groups of six or more, which reduces individual stress and promotes natural behaviour. Diet should mirror their omnivorous wild feeding — a quality staple supplemented with small live and frozen invertebrate foods. Any future husbandry notes would need to await specimens entering the trade or field observation.
Conservation
Enteromius okae has not been assessed by the IUCN Red List; its conservation status is Not Evaluated (NE). Small, restricted-range West African barbs frequently fall into this category due to limited survey coverage and the difficulty of assessing population trends for species with sparse baseline data.
The broader West African freshwater fauna faces significant and growing pressure from habitat modification — dam construction, agricultural water extraction, deforestation of riparian corridors, and pollution from mining and urban expansion. If Enteromius okae is a basin-endemic or range-restricted species, these regional threats may apply to it, but without confirmed distributional data a site-specific conservation assessment cannot be made. Targeted ichthyological survey work in its native catchment would be a prerequisite for any formal evaluation.