Histopathological analyses of liver and gill of Coptodon zillii obtained from Okerenkoko Waterfront, Delta State, Nigeria

Abstract

Pollutants and untreated anthropogenic effluents in surface water can cause abnormal changes in internal organs of fishes. Liver and gill are the most affected fish tissues due to their constant contact with toxins. Histopathological biomarkers are identifiable abnormalities in tissues of organisms predisposed to wide range of environmental pollutants. Information on histopathological biomarkers of fish from the Okerenkoko Waterfront (OWF) is limited. Hence, this study was carried out to investigate the effects of untreated effluents on the liver and gill of Coptodon zillii obtained from OWF. Samples of C. zillii were collected for four months using gill net of mesh size 24 mm. Liver and gill of farmed C. zillii were used as control. Harvested liver and gill of C. zillii were fixed in Bouin’s fluid and taken to laboratory for histopathological assay using standard procedures. The C. zillii harvested from OWF showed significant damage in selected organs. Liver tissues showed hepatocyte vacuolization, hepatocyte degeneration, necrosis, inflammation and sinusoids dilation, while gill tissues revealed uplifting of the primary epithelium, fusion, vacuolation, hypertrophy and necrosis. Liver and gill tissues of control C. zillii did not show any histopathological abnormalities in its liver and gills. Results from this study showed a positive correlation between the extent of tissue damage and surface water pollution. Findings from this study serve as baseline for future studies, while regular monitoring of pollutants in the OWF should be encouraged to protect its fish stock.