The study was conducted on 190Nile tilapia (Oreochromis niloticus) to evaluate the usefulness of the retrieved field isolate of probiotics (Pseudomonas fulva) by determining the in-vitro inhibitory effect against Aeromonas hydrophila. Ten fish were used to isolate the probiotic strain,60 fish were used to test the safety of the isolate and 120 fish used in the feeding experiment. The effects onthe growth performance and immune response werealso recorded after one and two months of the feeding experiment. The tested isolate showed an inhibitory effect against motile Aeromonassepticemia. The PCR of the isolated strain was identified as p.fulva12-X which seemed safe to tilapia by the intra-peritoneal injection. There was highly significant increase in the survival percent and body weight gain in the P.fulvatreated group < strong>. After one andtwo monthsof exposure, thenitroblue tetrazolium, lysozyme and phagocytic activities  in the P.fulva treated group was significantly increased. After challenge infection using A.hydrophila, the mortality percentage of P.fulvatreated group was 15%(with 81.25 % RLP)in comparison with the control group that showed 80% mortality. The histopathology of the treated groups were fully recorded in comparison with the control group after both treatment period and challenge infection. Weconcluded that, the isolate was useful to control motile Aeromonas septicemia. It enhanced the fish growth performance and immune response.