Effects of low dose γ-irradiation of fish product on spoilage potentials of bacteria (Aeromonas hydrophila, Salmonella typhimurium, Bacillus megaterium, and Pseudomonas marinoglutinosa) and mixed flora were examined for ability to proliferate in radurized fish and produce volatile acids (TVA) and bases (TVBN). Bacteria proliferated well in unirradiated and irradiated fish, but formation of VA and VB were lower in irradiated than unirradiated counterparts. This was found in Bombay duck, Indian mackerel, white pomfret, seer and shrimp gammairradiated at 0 to 5 kGy under ice. TV A and TVBN produced by the organisms or mixed flora from fish were only 30–50% those of controls. A method for identifying radiation-processed fish could evolve based on lower susceptibility of irradiated fish to bacterial spoilage.