Influence of Selected Water Quality Parameters on Fish Species Abundance in Eko-Ende Reservoir, Nigeria

Introduction This study was conducted to assess selected water quality parameters and evaluate their effects on fish species abundance and morphometric characteristics in the reservoir. Methods Monthly sampling of water and fish was done from the Sampling Points (SPA, SPB, and SPC) for 12 months. Results Temperature (23.19 ± 1.18°C) and pH (6.79 ± 0.92) were highest in SPB, dissolved oxygen was highest in SPA (4.21 ± 1.12 mg/L) and SPC (4.21 ± 1.14 mg/L), while ammonia was similar across the sampling points, with 0.02 ± 0.01 mg/L. The mean values of water quality parameters were highest in the dry season, and Student’s t-test indicated significant differences in temperature and ammonia between the wet and dry seasons (p < 0.05). The first principal component (PC1) (68.5%) and the second principal component (PC2) (24.3%) jointly explained 92.8% of the total variance, with ammonia and pH having negative values in PC1 (−0.551) and PC2 (−0.990), which indicated an inverse relationship to the PC. A total of 1,279 individuals (five families and nine species) were recorded. Coptodon zillii and Cichlidae were the most abundant species (17.59%) and family (60.3%), respectively. A very high correlation was observed between fish abundance and most water quality parameters. The length-weight relationship values were significant (p < 0.05) for Alestes baremose (b = 2.87, R² = 0.13) and Sarotherodon galileaus (b = 2.85, R² = 0.23), with a negative allometric growth pattern (b < 3), indicating that fish increase in length at a faster rate than in weight. Most K-values were greater than 1, which indicates a good condition for fish species. Conclusion The results suggest that the reservoir may provide suitable conditions for fish species, substantiated by the water quality and condition factor values. Hence, regular awareness of environmental management and fishing activities around the reservoir must be of the utmost importance for the maintenance of the water quality and the sustainability of fish species.