Effect of stress factors in the occurrence of Aeromonas hydrophila infection in cultured carp

In this research, the role of high temperature (up to 32ºC), water turbidity, fish crowdedness and oxygen deficiency on the occurence of in vitro infection due to Aeromonas hydrophila in cultured carp (common carp & silver carp) was examined. The fish with the weight 400 - 500 gr were kept in 60 liter aquariums and were bathed with 109 pathogenic Aeromonas hydrophila for one week. Then separate groups (with population of 10 for each) in separate aquariums were exposed to different stress conditions for 2 weeks. Diseased fish that showed skin hemorrhage and abnormal swimming were collected and their kidney tissues cultured on common bacteriology media. The obtained results showed that all the mortality were due to high temperature and no mortality was occured in water turbidity and crowdedness conditions. Isolation of Aeromonas hydrophila was only from the high temperature stress group. The results obtain from this study show that Aeromonas hydrophila is a potential pathogens for common carp and silver carp in stress conditions such as high water temperature