Taxonomy & naming
Enteromius dorsolineatus was described by Ethelwynn Trewavas in 1936, originally under the name Barbus dorsolineatus. The genus Barbus was long used as a catch-all for Old World barbs, but subsequent molecular and morphological revisions redistributed most African small barbs into Enteromius, a genus resurrected and expanded to accommodate the great diversity of sub-Saharan cyprinids that do not belong to the more restricted European Barbus sensu stricto. The valid combination, Enteromius dorsolineatus (Trewavas, 1936), reflects that reclassification; the parenthetical authority marks the move out of Trewavas's original genus.
The species epithet dorsolineatus is Latin for "line along the back" (dorso = back, lineatus = lined), a reference to the stripe running along the dorsal surface that gives the fish its alternative common name, Topstripe barb. The Catalog of Fishes (Eschmeyer, CAS) is the governing authority for the valid name and placement.
Morphology
Enteromius dorsolineatus is a small, slender barb of the typical small-Enteromius body plan — modestly elongate, laterally compressed, with a forked tail and the single pair of maxillary barbels characteristic of the genus. A dorsal stripe, from which the common name Topstripe barb derives, runs along the upper midline and is the most consistently noted external feature. Detailed morphometric data — precise standard length, fin-ray counts and scale counts — are not recorded in accessible English-language sources, and the species should be regarded as data-sparse in the aquarium literature.
Sexual dimorphism likely follows the general pattern of small Enteromius, with females becoming noticeably fuller-bodied when gravid and males potentially showing more intense coloration during spawning condition, though these observations have not been formally documented for this species.
Habitat
The Cunene barb is native to the Cunene and Cuito river systems along the Angola–Namibia border in southern Africa. The Cunene River runs approximately 1,31 mi from the central Angolan plateau to the Atlantic, draining a mosaic of highland forest, savanna, and seasonal floodplain habitats along its course. The Cuito, a major tributary of the Okavango, drains the southeastern Angolan plateau through a system of wetlands and forested watercourses of high conservation value.
Detailed habitat data for E. dorsolineatus specifically are sparse in the accessible literature. Related Enteromius species in comparable southern African river systems typically inhabit shallow, well-oxygenated streams and river margins, often over sandy or gravel substrates with riparian vegetation. Water chemistry in the Cunene basin varies with season and geology; pH values across related stream habitats in the region fall roughly in the 6.0–7.5 range, with temperatures in the mid-twenties Celsius for much of the year, though seasonal variation can be substantial.
Feeding
Like most small Enteromius, E. dorsolineatus is presumed to be an opportunistic omnivore, feeding on small invertebrates, algae, biofilm and fine organic detritus picked from the substrate and water column. This feeding mode is consistent across the genus in sub-Saharan river systems, where small barbs exploit the benthos and marginal vegetation for insect larvae, crustaceans and plant material.
No species-specific dietary studies have been published in the accessible literature. In captivity, the species would likely accept standard small barb rations — quality flake, small pellets, and live or frozen items such as daphnia, brine shrimp and bloodworm.
Mating
Enteromius dorsolineatus, like all barbs, is an egg-scattering, non-guarding spawner. No nest is constructed and no parental care is given. A gravid female is pursued by a driving male through available vegetation or over the substrate, and eggs and milt are released together in brief, close contact. There is no pair bond beyond the spawning act, and no territory is defended except transiently during active courtship.
The adhesive eggs sink among plants, roots or substrate particles once scattered. In the absence of predation pressure, the adults themselves represent the primary threat to the eggs, which they will consume if given access.
Breeding
No captive breeding records for Enteromius dorsolineatus appear in the hobbyist literature. The species has not been established in the aquarium trade and breeding data are lacking. By analogy with related small Enteromius, spawning would be expected to follow the standard small-barb pattern: adhesive eggs scattered among fine-leaved plants or over a gravel substrate, no parental care, eggs hatching within one to two days at tropical temperatures, and free-swimming fry emerging a few days later.
Seasonal cues — rising water temperature and possibly a simulated dry-to-wet transition — may trigger reproductive behaviour in the wild, consistent with the seasonally variable hydrology of the Cunene basin.
In the aquarium
Enteromius dorsolineatus is not established in the aquarium hobby and is unlikely to be encountered in the trade. The species has not been bred in captivity to any documented extent, and there are no published husbandry accounts. Its range in the Cunene and Cuito river systems of Angola and Namibia places it outside the areas most heavily surveyed for the aquarium trade.
Should specimens become available, general Enteromius husbandry would apply: a modestly sized, well-filtered tank with neutral to slightly acidic water, a fine sandy or gravel substrate, some cover in the form of plants or driftwood, and a diet of varied small foods. Like all barbs it would be expected to show best colour and natural behaviour when kept in a group of at least six.
Conservation
Enteromius dorsolineatus is assessed as Least Concern (LC) on the IUCN Red List. The Cunene and Cuito river systems in southern Angola and northern Namibia retain relatively intact catchments compared with more heavily developed parts of Africa, and the species is not known to face acute threats at a range-wide level.
Nonetheless, freshwater biodiversity in the Cunene basin is subject to pressure from hydroelectric development — the Ruacana Falls complex and other infrastructure projects on the Cunene — as well as agricultural water extraction and the long-term effects of climate variability on seasonal flow regimes. As a small-bodied endemic of a specific regional drainage, E. dorsolineatus has a naturally limited range, and continued monitoring of the basin's fish community would be warranted as development of the Angolan interior proceeds.