Taxonomy & naming
Enteromius atakorensis was described by Jacques Daget in 1957 and originally placed in the genus Barbus, the broad catch-all that housed virtually all Old World small barbs through most of the twentieth century. The name is rendered as Barbus atakorensis Daget, 1957 in older literature. The Catalog of Fishes (Eschmeyer, CAS) recognises the current valid combination as Enteromius atakorensis (Daget, 1957), the parenthetical authority marking the generic transfer. The genus Enteromius Cope, 1867 has been reinstated to accommodate the large African radiation of small barbs that had accumulated within the wastebasket Barbus, following the phylogenetic work that restricted the name Barbus sensu stricto to European and North African lineages.
The species epithet atakorensis refers to the Atakora range — the chain of hills running through northern Benin and north-western Togo — whose upland streams drain into the Oti River system, part of the Volta basin. The type locality is in that drainage. No subspecies or colour morphs are formally recognised.
Morphology
Detailed morphometric data for Enteromius atakorensis are sparse in the available literature, as the species has not been the subject of a dedicated redescription since Daget's original account. It is a small, slender-bodied barb, consistent in general proportions with other small Enteromius of the West African savanna zone — typically reaching no more than 2–3 in in standard length. The body is moderately laterally compressed, the head relatively small, and the mouth subterminal with one or two pairs of barbels as is typical for the genus.
Colouration in preserved specimens, as described from the type series, is a pale silvery-brownish ground with darker scale margins producing a reticulate pattern; details of live colouration are not reported in the accessible literature. Sexual dimorphism has not been formally described for this species, though in closely related Enteromius, females are typically deeper-bodied when gravid and males may show brighter flank colouring.
Habitat
Enteromius atakorensis is native to the Oti River drainage in the Volta basin, specifically from the upland and foothill streams associated with the Atakora range in northern Benin and Togo. This region lies in the Sudano-Guinean transition zone, where forest galleries give way to wooded savanna and seasonal grassland. Streams here are typically clear to slightly turbid, with sandy to gravelly substrates, moderate current over riffles, and slower pools fringed with emergent vegetation.
Water chemistry in these West African savanna headwaters is generally soft to moderately hard, slightly acidic to neutral (pH roughly 6.5–7.5), and warm year-round, with temperatures broadly in the range of 75–82 °F. The Atakora streams experience a pronounced dry season during which smaller channels may shrink drastically, concentrating fish in pools; the wet season brings spate conditions and expansion into floodplain margins. The species has not been recorded from the main channels of the larger Oti or Volta rivers.
Feeding
No dedicated dietary study of Enteromius atakorensis has been published. Based on gut-content analyses of ecologically similar small Enteromius from comparable West African savanna streams, the species is presumed to be an opportunistic omnivore. This feeding guild typically consumes small aquatic invertebrates — chironomid larvae, microcrustaceans and aquatic insects — alongside filamentous algae, diatoms, and organic detritus gleaned from the stream bed.
The subterminal mouth and small body size are consistent with benthic foraging over sand and gravel substrates. In seasonally flooded habitats, terrestrial insects and plant material washed into the water likely supplement the diet during the wet season, as is documented for many small barbs in comparable African stream systems.
Mating
Enteromius atakorensis, as a member of the barb family, is an egg-scattering, non-guarding spawner. No published account of its reproductive behaviour in the wild exists, but the mating system follows the pattern universal among Enteromius and cyprinids generally: a gravid female is pursued through vegetation or over the substrate by one or more males, and eggs and milt are released briefly in contact, with no pair bond formed.
In West African savanna stream barbs, spawning is typically seasonal and tied to the onset of the rains — rising water levels, increasing current, and a drop in temperature relative to dry-season pools stimulate reproductive activity. Males in breeding condition may show intensified colouration, though this has not been formally documented for this species. No nesting, territory holding, or nest construction is involved.
Breeding
Reproduction in Enteromius atakorensis has not been reported from either the wild or captivity in any accessible source. By analogy with other small West African Enteromius, spawning is seasonal and corresponds to the onset of the rainy season in the Oti basin, roughly May to September. Eggs are adhesive and scattered among fine-leaved vegetation, submerged roots or over gravel; parents provide no care and will consume eggs if encountered.
Fecundity figures, incubation period and larval development have not been published for this species. Given its small adult size, clutch sizes are likely modest by cyprinid standards. The species has not entered the aquarium hobby in any significant numbers and has not been bred in captivity under controlled conditions.
In the aquarium
Enteromius atakorensis is essentially absent from the aquarium hobby. It has never been commercially collected or exported in meaningful numbers, and no husbandry literature exists for it. The species is unlikely to appear in the trade given its very restricted known range, the remoteness of its habitat in northern Benin and Togo, and the lack of any ornamental interest that would motivate targeted collection.
If it were to be kept — by a specialist working with regional faunas — the appropriate conditions would mirror its native savanna stream habitat: a roomy tank with a sand or fine gravel substrate, moderate water flow, a temperature of 75–82 °F, near-neutral pH (6.5–7.5), and soft to moderately hard water. Being a small shoaling barb, it would be expected to require conspecific company and would likely accept standard small-particle foods. Any such account would be speculative until the species is actually maintained and observed.
Conservation
Enteromius atakorensis is assessed as Least Concern on the IUCN Red List. The species' known range — the Atakora River drainage of northern Benin and the adjacent Togo highlands — is a geographically restricted area, though the Least Concern listing indicates it is not currently considered at elevated risk despite ongoing pressures including seasonal water extraction for agriculture, sedimentation from deforestation of the Atakora foothills, and the degradation of gallery forest along stream margins.
The Volta basin as a whole has experienced significant hydrological modification, most notably from the Akosombo Dam and associated impoundments, though the Atakora headwaters are not directly affected. Continued monitoring of the range, population size and ecological requirements of E. atakorensis would still help confirm this status over time, and the documented fragility of small headwater endemics in the Guineo-Sudanian transition zone means local conditions are worth watching even where the species-wide picture is currently reassuring.