Lethal Effects of Zinc and Nickel on Freshwater Teleosts

Static bioassays were conducted at 20.5£C and the hardness of 260 ppm as CaCO₃ with zinc sulphate and nickel sulphate using Puntius sophore, Rasbora daniconius neilgeriensis, Channa punctatus and Lebistes reticulates. The 96 h LC50 values for all four fish species ranged from 29.88 to 54.95 £ of zinc and 13.57 to 48.83 £ of nickel. Channa punctatus were consistently more sensitive to zinc, while Puntius sophore were to nickel. The behavioural changes, such as loss of equilibrium and shoaling nature, swimming with their bellies upwards and irregular opercular movement were noted.