Influence of habitat structures on fish abundance and diversity: a case study of rural river in North Central eco-region of Nigeria

Human activities have put considerable pressure on the dynamics and overall health of dominant fish species in aquatic ecosystems. In this study, we investigated the influence of habitat structures on fish abundance and diversity in Wanzum River, a rural River within the North Central eco-region of Nigeria. We selected four sampling stations along the river that represent various levels of anthropogenic activities. The samples were collected for a period of twelve (12) months (December 2021–November 2022) and were analysed using standard methods and procedures. A total of 1,470 individual fish belonging to 19 species, 14 families and 9 orders were recorded. Cichlidae was the most abundant family, represented by Oreochromis niloticus (22.99%), Tilapia zillii (20.27%) and Hemichromis fasciatus (3.94%). Clariidae was the second most dominant family, with Clarias gariepinus (15.71%) and Clarias anguillaris (8.29%). The diversity indices revealed the highest species richness at Station 1 (18 species) and the lowest richness at Station 3 (14 species). The Shannon–Weiner index values ranged from 2.012 (Station 3) to 2.317 (Station 1), while Simpson’s index indicated relatively high diversity across stations (0.813–0.865). Canonical correspondence analysis showed that fish distribution was influenced by depth, dissolved oxygen, biochemical oxygen demand, pH, and electrical conductivity, though the relationships were not statistically significant (p > 0.05). These findings highlight that fish abundance and diversity in the Wanzum River are shaped by habitat structures and anthropogenic pressures. Effective management of habitat quality is therefore critical for sustaining fish biodiversity and ensuring the ecological health of rural rivers in North Central Nigeria.