Toxicological Effects of Crude Oil on the Histopathology of Selected Organs in African Catfish (Clarias Gariepinus Burchell, 1822) (Published)
A twenty-eight (28) day study investigated the toxicological effects of crude oil on the histopathology of selected organs in African catfish (Clarias gariepinus Burchell, 1822) as a bioindicator organism. The research was conducted to evaluate the impact of varying concentrations of crude oil on water quality parameters, swimming and feeding behaviour, mortality rate, and histopathological changes in vital organs of the fish. A laboratory-based experimental design was adopted, where fish were exposed to different concentrations of crude oil (10 ml, 20 ml, 40 ml, 80 ml, and 160 ml) alongside zero (00 ml) control. Physicochemical parameters such as temperature, pH, dissolved oxygen (DO), and water hardness were measured. Results showed a progressive increase in water temperature and hardness with increasing crude oil concentration, while pH and DO levels decreased significantly, indicating deterioration in water quality. Mortality rates increased with both concentration and exposure time, with the highest mortality recorded at 160 ml. The histopathological examination revealed severe tissue damage in exposed fish with increased concentration of crude oil. Observed alterations included lamellae damage, epithelial lifting, and mucus accumulation in the gills; cellular degeneration, vacuolation, and necrosis in the liver; and tubular degeneration and shrinkage of glomeruli in the kidney. These changes demonstrate that crude oil exposure significantly impairs respiratory, metabolic, and excretory functions in fish. The study concludes that crude oil pollution poses serious threats to aquatic organisms and ecosystems by degrading water quality, increasing mortality, and causing structural damage to vital organs. It is therefore recommended that stricter environmental regulations and effective oil spill management strategies be implemented to protect aquatic biodiversity and sustain the community’s livelihood.
Keywords: Bioindicator, Clarias Gariepinus, Toxicity, crude oil, histopathology