Histopathologic changes in the gills and skin of adult Clarias gariepinus exposed to ethanolic extract of Parkia biglobosa pods

Background and aim: Fish live in direct contact with their immediate external environment and, therefore, are highly vulnerable to aquatic pollutants. We aimed to investigate histopathologic changes in the gills and skin of fish exposed to plant extracts. Methods: Clarias gariepinus adults were exposed to 0 mg/L, 85 mg/L, 100 mg/L, 115 mg/L, 130 mg/L and 145 mg/L concentrations of ethanolic extracts of Parkia biglobosa pods over a 96-h period. Results: Gills from exposed fish showed hyperemia and severe edema with fusion of secondary lamellae. The skin from exposed fish showed hyperplasia of mucus producing cells, epidermal and dermal polymorphonuclear leukocytic infiltrations with areas of dermal necrosis and aggregation of melanin pigments. Fish from the control group showed no histopathologic changes. Conclusions: Ethanolic extract of P. biglobosa pods is toxic to adult C. gariepinus. Therefore, extensive use of this tree to harvest fish for human consumption should be discouraged pending further investigations to determine the safety of such practices to human health.