Author(s): Patrick Ozovehe Samuel, Loveline C Okoye, Paul O Abiola, Francis O Arimoro and Yohanna I Auta

Abstract: Acute toxicity assessment of lead nitrate ((PbNO₃)₂) on post juvenile Clarias gariepinus under laboratory conditions were investigated. A total of 150 samples of the fish were acclimatized for two week. 6 aquaria tanks were set-up for determination of the 96hours LC₅₀ with 6 samples of fish per tank. The lethal concentration values of lead nitrate used were 240mg/L, 260mg/L, 290mg/L, 320mg/L and 34mg/L with replicate in each case. The control setup was without the toxicant. The fish samples exhibited varying behavioural and physical changes which ranged from erratic swimming, poor feeding habit, frequent gasping for air at the surface of the tank, lacerations of the skin and secretion of mucus, and eventually death. The vigour and severity of these features were time and concentration dependent. The results showed that 96hours LC₅₀ of Clarias gariepinus was 284.189mg/L. This indicated that greater quantity of the toxicant is needed to cause mortality in the fish and less deleterious at lower concentrations.

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