Four environmental bacterial isolates, including Aeromonas hydrophila, Aremonas soberia, Aremonas veronii, and Vibirio cholerae, were isolated from living Carp in some farms in Babylon, Iraq, and examined for their responses to temperature, pH, and incubation period under laboratory conditions in this study. In addition, bacterial growth under test conditions was measured to obtain important parameters related to bacterial growth, lag time (λ), specific growth rate (μm), and maximum biomass (A) for comparison. V. cholerae did show the lowest mean growth at different temperatures, but was adapted to a much wider environmental pH from 4 to 9 for growth, while A. hydrophila was more adaptable to pH and temperature changes, yielding the highest mean biomass at pH 8 and temperature 40 °C. A. sobria was surprisingly tolerant to different incubation periods and grew almost equally well under the conditions of other treatments. All four bacterial isolates showed a wide spectrum of plasticity to environmental conditions, and they pose a potential threat to public health and animal health.