A new minnow species, Enteromius thespesios, is described from the south‐eastern part of the upper Congo River; that is, the Kalule Nord, the Luvilombo and the Chambeshi Rivers. Enteromius thespesios belongs to the group of the soft‐rayed species of Enteromius from the Congo Basin; that is, those with a weakly ossified, flexible last unbranched dorsal‐fin ray that lacks serrations along its posterior edge. Within this group, E. thespesios is most similar to E. humeralis, from which it is distinguished by a higher number of circumpeduncular scales and shorter anterior and posterior barbels. Enteromius thespesios is a rheophilic and territorial species. It exhibits a marked sexual dimorphism, with males having: a red band towards the distal edge of dorsal, caudal and, to a lesser degree, anal fin; nuptial tubercles; a longer snout; longer pectoral fins; a shorter anal fin. This study gives extensive consideration to sexual shape differences for a species of Enteromius and also briefly reviews the current knowledge of sexual dimorphism in the species of Enteromius from the Congo Basin. Some conservation issues related to the new species are also highlighted.

The fish diversity of the Kundelungu National Park (KNP), one of the seven national parks of the Democratic Republic of the Congo, has never been thoroughly studied. This first checklist is presented based on a literature compilation and the study of historical (1939–1969) and recent collections (2012–2017). A total of 96 taxa are reported, including 64 native described species, one introduced species (Poecilia reticulata), 13 new species that await formal description and 18 possibly new species that require further investigation to verify their status. These taxa represent 39 genera and 17 families from the KNP including its Buffer Zone (BZ). Only six taxa, including five endemics, are known from the Core Zone on the Kundelungu Plateau (1300–1700 m alt.). At lower altitudes (800–1100 m), in the Annex Zone, 71 taxa, including 17 endemics, were found. Finally, 50 taxa, including 13 endemics and one introduced species, are known from its BZ. The fish fauna of the KNP is threatened by overfishing, destructive fishing practices, and habitat degradation due to mining pollution, and deforestation for agriculture on the river banks. The present study provides the much needed baseline data for the protection and conservation planning of this fish fauna, for which conservation suggestions are formulated.

An annotated checklist of the ichthyofauna of the Upemba National Park, draining part of the Upper Lualaba basin and situated in the southern part of the Democratic Republic of the Congo, is presented, based on a literature review, a re-examination of museum collections, and a study of recent collections (2012–2020). In total, 247 native and 1 introduced species, Heterotis niloticus, are reported. The native species belong to 78 genera, 26 families, and 15 orders. Of these, 45 species (18%) are endemic to the park, 35 species (14%) await formal description, and 5 taxa (2%) need further study to clarify their status. With 51 species, the Cyprinidae is by far the most species-rich family, followed by the Mormyridae (26), Mochokidae (26), Alestidae (18), Distichodontidae (18), Amphiliidae (17), and Cichlidae (16). The remaining families are represented by less than 15 species. Comments about the species distribution and the fish fauna shared with adjacent ecoregions are provided. Although the park provides some protection for the fish species living within its borders by limiting human access to the core zone, the annex and buffer zones are both subject to strong anthropogenic pressure. These observations underscore the need for the implementation and further elaboration of fish-related preservation guidelines and plans to enable better protection/conservation of the park’s ichthyofauna.

This study examined the effects of pollution from the Shituru hydrometallurgic complex on the Upper Lufira Basin, Democratic Republic of the Congo, between September 2015 and September 2017. Physico-chemical water variables and trace metal elements in water and sediment, as well as diversity and infection parameters of monopisthocotylan parasites infesting Clarias ngamensis, were assessed at three sites: the Lufira River, Panda River, and Lake Tshangalele. We hypothesised that low pollution would correlate with greater ectoparasite species richness and higher infection parameters. Results indicated severe ecological degradation in the highly polluted Panda River (with high concentrations of TMEs; e.g., 510.830 ± 0.86; 82.470 ± 0.200 µg/L for Co²⁺ and Cu²⁺ in water; 15,771 ± 7068 and 1585 ± 1450 µg/g for Cu²⁺ and Zn²⁺ in the sediment), where neither fish nor parasites were present. Across the other sites, eight parasite species were identified. Seven species occurred on fish from the slightly polluted Lufira River (mean intensity (MI) of 31.28 ± 28.95 parasites per infested fish), while five were found in Lake Tshangalele (MI: 3.23 ± 2.89 parasites per infested fish), confirming the hypothesis. Three species, Quadriacanthus halajiani, Q. domatanai, and Macrogyrodactylus clarii, demonstrated potential as sensitive bioindicators of aquatic pollution in the region.