Abstract: Micronucleus formation in fish cells, as an indicator of chromosomal damage, has been increasingly used to detect the genotoxic potential of heavy metal exposure. This study was investigated the effects of cadmium (Cd) and ascorbic acid (AA) on the red-tailed tinfoil barb (Puntius altus) using the micronucleus (MN) and nuclear abnormality (NA) tests for the period of 24, 48, 72 and 96 h. The MN frequencies in the erythrocytes, gill, liver and fin cells were analyzed comparatively to evaluate the sensitivity and suitability of these different cell types. NA shapes in erythrocytes were scored into blebbed nuclei (BL), lobed nuclei (LB), notched nuclei (NT) and binuclei (BN). It was observed that, fish showed significant sensitivity to the different treatments. In general, the highest value of both MN and NA cells were significantly increased in the Cd treated group followed by the combination of Cd and AA treated group. On the other hand, the MN and NA frequencies in erythrocytes were the most sensitive to the treatment and could provide valuable information than those in gill, liver and fin cells. The frequencies of each NA shape in erythrocytes of all treatments were observed in the following NT > LB > BN > BL. Results of MN and NA revealed the highest number after 48 h treatment in all cases and decreased within the longer time exposure. Our results demonstrated the efficacy of AA in reducing genotoxicity in fish induced by Cd. Otherwise; they showed the sensitivity and suitability of MN and NA frequencies in erythrocytes for pollution biomarkers.