Abstract: The piscine erythrocyte micronucleus assay is a proven and sensitive indicator of DNA damage. Recently, several nuclear and cytoplasmic abnormalities other than Micronuclei (MN) have drawn wide attention. These include Nuclear Bud (NBu), Lobed Nucleus (LN), Nuclear Bridge (NBr), Anisochromasia (AN), Vacuolated Cytoplasm (VC) and Vacuolated Nucleus (VN). The importance of these nuclear abnormalities as biomarkers of exposures has not been previously exploited. In the present study an effort was made to compare the occurrence and frequencies of these nuclear abnormalities in fish exposed to sublethal concentrations of the insecticide Monocrotophos (MCP), herbicide butachlor and ionizing radiation in an effort to identify biomarkers specific to ionizing radiation and to validate these biomarkers for use in genetic toxicology studies. Among the various abnormalities, the occurrence of NBr was observed only in fishes exposed to ionizing radiation. The frequencies of NBu were significantly elevated in fish exposed to radiation. These observations indicate that NBr and elevated frequencies of NBu are likely indicators of radiation genotoxicity. The authors propose the erythrocyte MN assay to be more aptly renamed the ‘erythrocyte micronucleus cytome assay’ (ECMNA) considering the prospects of extending its applications in aquatic cyto-genotoxicity.