Abstract

Fish is sensitive to devastating consequences of oil contamination. Histological changes in Clarias gariepinus fingerlings before death under exposure to different concentrations of spilled engine oil was carried out. The study examined the effect of spilled engine oil, on the phsico-chemical parameters in water, determined the effect of spilled engine oil, on the kidney of catfish (Clarias gariepinus) and evaluation of the behavioral responses of fish at different concentration of spilled engine oil. Three hundred and sixty Clarias garinepinus fingerlings of average weight 3.50± 0.01g and length 12 ± 0.000m was exposed to different concentrations of (0.01, 0.03 and 0.05 ml/L) of oil with fifteen (15) fishes per tank in two replicates. The median lethal concentration (LC₅₀) value of spilled engine oil on Clarias gariepinus fingerlings was found to be 0.05m1/L of water. Each treatment was subjected to 96 Hour bioassay test to determine its acute toxicity in a completely randomized design experiment. Changes in water quality and fish mortality in all treatments were monitored daily in addition, behavioural and histological responses were also investigated. There was a significant difference (p<0.05) in values of temperature, electrical conductivity, salinity, pH and Dissolved Oxygen among all the treatments before and after the experiment. Mortality rate was highest (90%) in fish exposed to 0.05ml/L spilled engine oil water at 96hrs exposure. As concentration and time of exposure increased, the fish showed restlessness, rapid opercula movement, erratic swimming, discoloration and loss of reflex before death.