The fingerlings of Tilapia zilli (mean weight 7.95 ± 0.33g) were exposed in glass aquaria to acute concentration of urea fertilizer for a period of 96 hours. The 96hr LC50 of the exposed fish was determined to be 15.85 gl-1 with lower and upper confidence limits being 8.85 and 28.46 gl-1 respectively. During the exposure period, the fish stood in upright position with their snouts above the water surface gasping for air. Other behavioural reactions of the exposed fish observed before death were uncoordinated swimming, restlessness, frequent attempts at jumping out of the tank and quietness. Water quality examination showed a decrease in the dissolved oxygen content and increase in total dissolved solute, conductivity, alkalinity and free carbon dioxide as the concentration of the fertilizer was increased. The toxicological implications of these findings in relation to environmental pollution are discussed. Keywords:Urea fertilizer, Acute toxicity, Tilapia zilli Bio-Research Vol. 6 (1) 2008: pp. 298-300
PC Ofojekwu, CD Nwani, RE Ihere
