Studies on the genotoxic effect of cadmium chloride in three tissues viz., RBCs, kidney cells and gill cells of a fresh water fish Channa punctatus has been carried out using the micronucleus test. The fishes were treated with four sub-lethal concentrations of cadmium chloride i.e., 1.0, 2.0, 4.0 and 8.0 mg/l. The exposed and controlled fishes were sacrificed after 24, 48, 72 and 96 hrs of exposure. Formation of micronuclei was observed to occur in RBCs, kidney cells and gill cells after heavy metal treatment. Aim of the present investigation was to determine the dose and time dependent induction of frequencies of micronuclei in different tissues examined. A comparison between micronucleus frequencies in all the tissues revealed highest micronucleus frequencies in gills followed by RBCs and least in kidney cells. Results from this study recommend the use of the micronucleus test in fish tissues as a sensitive monitor for aquatic pollution. The results also show that the assay can be employed for the evaluation and the assessment of water pollution and aquatic mutagens.
