ABSTRACT

A 96 hour bioassay was conducted to determine the toxicity of cassava effluent to Claries gariepinus juveniles and its effects on the gills and liver as well as on some blood parameters such as packed cell volume (PCV), Red blood cells (RBC), White blood cells (WBC), Haemoglobin concentration (Hb) and their counts. Juveniles of C. gariepinus of the same age and size showed varying degrees of hyper-activity, mortality, stress and lesions to different concentration of cassava effluent. Static bioassay test revealed the 96 hour LC5o of cassava effluent as 4.365ml/L, exposure to sublethal concentration of cassava effluent resulted in the reduction of blood parameters such as PCV, RBC and Hb however, the value of white blood cells increased at the end of the experiment. Degenerative and erosive changes were observed on the tissues of the organs of C. gariepinus. The gills of fish in the varying concentrations particularly the higher concentrations (5.00ml/L and 5.50ml/L) showed signs of necrosis which means that at those concentrations cassava effluent is too toxic to C. gariepinus juvenile. The liver of fish in higher concentrations also showed hydropic degenerative changes such as space formation. Water quality parameters monitored during the experiment changed (temperature, Ph and Oxygen), the pH increased considerably throughout the course of the experiment, the dissolved oxygen concentration values recorded during the experiment decreased. Exposure to cassava effluent will prevent oxygen dissolution, cause destruction of breeding grounds as well as fish eggs, and ultimately, alteration of the entire aquatic environment leading to high mortality or total eradication of aquatic life.