Effect of using AHɸ3 bacteriophage in the survival rate of Rainbow trout (Oncorhynchus mykiss) contaminated with Aeromonas hydrophila in in vivo condition

Aeromonas hydrophila bacteria causes septicemia in saline and fresh water fishes. One of the most important problems in the field of health management in some fish farming centers is controlling the bacterial septicemia syndrome caused by this bacterium. The purpose of this study was to find a way to control and eliminate the bacteria using bacteriophage to increase the survival rate of rainbow trout, infected with Aeromonas hydrophila bacteria. In this research was carried out in the years 2018-19, 360 rainbow trout weighing 15±2 grams in 24 aquariums were selected in 15 groups with 3 replications. They were contaminated with a concentration of 10-4 and 10-8 Aeromonas hydrophila (prepared from stock containing 1.5× 108 CFU / ml, both intraperitoneally and immersed in water. Then they were exposed to 10-3 PFU/ ml AHɸ3 bacteriophage isolated from rainbow trout farming pools of Kerman province. Temperature, pH, Oxygen, Salinity was controlled for all treatments. There was a significant difference between the control group and the treatments in both cases (intraperitoneal injection and immersion) (P <0.05). The results indicated that the highest effect of bacteriophage on survival rate and reduction of rainbow trout losses was observed when the concentration of 10-8 bacteria and 10-3 PFU/ ml bacteriophage AHɸ3 were immersed. The data were analyzed using SPSS 21 software and Duncan statistical test. Suitable and applied to increase the survival rate of rainbow trout against disease bacteria is the use of bacteriophages.