Effects of Lead Chloride on Growth Performance of Clarias gariepinus (Burchell, 1822)

Abstract

The study determined the median Lethal Concentration (LC50), investigated the growth and behavioral response of Clarias gariepinus to sub-lethal concentration of lead chloride in a static renewal bioassay. Acute toxicity test was carried out using different concentrations of lead (350, 400, 450, 500, 550 mg/L) in a statics bioassay for 96 hrs to assess median lethal concentration of lead on the fish. The concentrations used for the sub-chronic toxicity test were based on the results obtained from the acute test. A static renewal bioassay procedure was adopted in which the test culture was regularly renewed every 48 hrs at the set concentrations of PbCl2 (0, 20, 40, 60, 80, 100, mg L−1). The growth and behavioral response and as well as the mortality response were monitored for the 21 days of exposure. Data obtained were analysed using Analysis of Variance (ANOVA). The results showed an LC50 of 426 mg/L. Sublethal exposure showed a decrease in growth rate with an increase in PbCl2 concentration. The value of specific growth rate (1.95 ± 0.015 mg/L) of fish in the control tank was significantly (p<0.05) higher than the other level of PbCl2 concentrations. The fish behavior was normal through-out the period of experiment (21 days) with some exceptions where there was erratic movement in high concentration (80 mg/L and 100 mg/L), lethargy and vertical positioning majorly after 48 hrs prior to changing of the water. The study concluded that lead metal (heavy metal) has negatively impacted on Clarias gariepinus with a reduction on growth performances and behavioral response.