Behavioural Toxicity of a Combined Oilfield Chemicals on African Catfish (Clarias gariepinus) (Burchell 1822)

Abstract

The toxicity of the combination of xylene and diesel at a 50:50 ratio on the African catfish (Clarias gariepinus) was investigated using a static bioassay for 96hrs. No significant difference (P>0.05) was observed in the Physicochemical parameters of the experimental water after exposure for 24 hours among the different concentration gradients and the controlled unit. Although there was an increased variation along the concentration gradient observed after 96hours. The behavioral responses of the test fish from 24-96 hours of exposure show normal behavioral responses in the control. C. gariepinus exposed to 25 ml/l to 50 mg/l concentration of the toxicant showed normal behavior from 24 to 48 hours. Afterward, the fish that were active stopped swimming and remained static for a while in response to the sudden changes in the surrounding environment. Generally, fish exposed to higher concentrations such as 100 ml/l to 250 ml/l of the test chemicals showed progressive hyperventilation and abnormal behavior like gulping air, erratic swimming movement, very fast swimming, jumping, and displaying vigorous jerky movement suffocation, and loss of reflex. A faster operculum and tail beat movement was also observed with Spiraling. The behavioral responses increased significantly (P<0.05) with an increase in concentration per time as compared to the control group of fish. The noticeable behavioural difference was recorded for the different concentrations of the test chemical. An eco-friendly chemical that is within the acceptable limits recommended by WHO and DPR should be used in well stimulation and cleaning for sustainable biodiversity and a healthy aquatic environment.