Most rivers and reservoirs in the world are prone to pollution because of indiscriminate disposal of domestic, agricultural and industrial wastes into the water bodies. In this study, we investigated the ecotoxicological potential this could pose in fish species collected from major reservoirs and rivers in Ilorin, north central, Nigeria. Water samples were collected and the physicochemical parameters were examined from five different sites; Unilorin reservoir, Asa reservoir, Apodu reservoir, Asa river (Unity) and Asa river (Harmony). We determined serum biochemical (AST, ALT, ALP, serum ALB), histopathological (gill, lungs), serum antioxidant enzyme responses (SOD, CAT, GPx, GR, GST) which serves as a biomarker for evaluating oxidative stress while micronucleus and comet assays were used to detect level of DNA damage in Tilapia zillii and Clarias gariepinus. The physicochemical parameters and heavy metal analysed (Pb, Mn, Cu, Ni, N, P, Fe, Cl, and Ca) in the five different water bodies were below the permissible limits of WHO and USEPA except the DO, which was very low in the two rivers, indicating hypoxia. Our results showed significant increase in biochemical and hematological profiles, histopathological lesions in the gill and lungs, inductions of MN, NA and DNA single strand break in Tilapia zillii and Clarias gariepinus collected from Asa rivers compared to the Unilorin, Apodun and Asa reservoirs. This may be attributed to indiscriminate discharge of effluents from nearby industries, agricultural and domestic wastes into the rivers.

Indiscriminate discharge of home, agricultural, and industrial wastes into water bodies, most rivers and reservoirs around the world are becoming polluted. The ecotoxicological potential of this in fish species gathered from important reservoirs and rivers in Ilorin, Nigeria, was explored in this study. Unilorin reservoir, Asa reservoir, Apodu reservoir, Asa river (Unity), and Asa river (Unity) water samples were collected and physicochemical characteristics were investigated at five distinct sites: Unilorin reservoir, Asa reservoir, Apodu reservoir, Asa river (Unity), and Asa river (Unity) (Harmony). In Tilapia zillii and Clarias gariepinus, we measured serum biochemical (AST, ALT, ALP, serum ALB), histopathological (gills, lungs), and serum antioxidant enzyme responses (SOD, CAT, GPx, GR, GST) as a biomarker for oxidative stress, while micronucleus and comet assays were used to detect DNA damage. Except for DO, which was very low in the two rivers, the physicochemical parameters and heavy metals evaluated in the five separate water bodies were within the allowed levels of the NSDWQ and WHO standard for drinking water. In comparison to the Unilorin, Apodu, and Asa reservoirs, a slight increase in Pb was observed across the five sampling sites, which could contribute to increased biochemical and haematological profiles, histopathological lesions in the gill and lungs, inductions of MN, NA, and DNA single strand break in T. zillii and C. gariepinus collected from Asa rivers. This could be due to the indiscriminate dumping of effluents from adjacent industries, agricultural wastes, and household wastes into rivers.