The present investigation was undertaken to study the induction of DNA damage by CdCl₂ in freshwater climbing perch Anabas testudineus (Bloch) using alkaline single cell gel electrophoresis (comet assay). The DNA damage was measured in the tissue of gill, kidney and liver as the percentage of DNA in comet tails and comet heads in the tissue of the fish specimens exposed to 0.1, 1.0, 2.0mgL⁻¹ concentrations of CdCl₂. It was found that at all the concentrations of CdCl₂, the liver tissue exhibited significantly (p<0.01) higher DNA damage, followed by kidney and gill tissue. The DNA damage was found to be concentration dependent, with the highest DNA damage at 2mgL⁻¹ concentration, followed by 1.0 and 0.1mgL⁻¹. At the concentration of 2mgL⁻¹ of CdCl₂, the tail and head DNA of liver tissue were 38.81% and 59.49%, in kidney tissue the values were 32.37% and 64.66% whereas in gill tissue the values were 31.30% and 66.40% respectively. This study conclude that comet assay can be used for in vivo laboratory experiment using fish as model for screening the genotoxic potential of cadmium.