Histo-toxicity of Corexit 9500 Dispersant on Gill and Liver of Clarias gariepinus (Burchell 1822)

The aim of this study was to assess the chronic toxicity of Corexit 9500 on histology of liver and gill of juveniles of Clarias gariepinus. Range finding tests were conducted over a 96-hr period after acclimatization of the test organisms in the C.P. Powell laboratory in the University of Port Harcourt, Nigeria. The test organisms 10/treatment were exposed to the following concentrations of Corexit 9500; 0.00 ml/L, 0.0125 ml/L, 0.025 ml/L and 0.05 ml/L in triplicate. Liver and gill were excised from fish every week for histological assay using standard methods. The LC50 at 96 hrs was 0.115 ml/L. The growth in length and weight of C. gariepinus was significantly higher in the control than the test treatments (p<0.05). Hyperplasias, necrosis of epithelial cells, inflammation of the secondary gill lamella and hypertrophic primary gill lamella were observed in the exposed gills. Hepatic lesions in the liver tissues of the fishes exposed to Corexit 9500 were characterized by hyperplasia, narrowing of the central vein and vacoulations. The alterations observed in the liver and gill tissues indicated that Corexit 9500 may have interfered with transamination and metabolic processes, with the possibility of affecting the physiological functions of the fish in an aquatic environment.