Acute toxicity of mercury to Oreochromis niloticus fingerlings

Abstract

Fingerlings of Oreochromis niloticus were exposed to the following mercury (as HgCl₂) concentrations: 0.005, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06 mg l^-1 Hg of water. Hyperactivity and erratic swimming were the first indications of mercury intoxication. Scoliosis, a curvature in the mid-trunk region, was observed in some fish in the 0.03 - 0.06 mg l^-1 Hg tanks. The occurrence of scoliosis is significantly correlated with mercury concentration. The 24 hour LC₅₀ (0.0375 mg l^-1 Hg) did not differ significantly with the 96 hour LC₅₀ (0.0350 mg l^-1 Hg).