从患出血病罗非鱼的血液、肝、脾分离出嗜水气单胞菌 (Aeromonashydrophila) ,经动物回归和理化试验鉴定 ,确诊嗜水气单胞菌为罗非鱼出血病病原 ;用分离菌制成的饵料吸附型疫苗进行田间试验 ,免疫组罗非鱼保护率为 87.1%,未免疫组存活率为 5 9.9%,两组间差异极显著 (P <0 .0 1) Aeromonas hydrophila was isolated from the blood, liver and spleen of hemorrhagic tilapia, and identified by animal regression and physico-chemical test. The results showed that Aeromonas hydrophila was the pathogen of tilapia hemorrhage. The results showed that the protective rate of tilapia was 87.1% in immunized group and 59.9% in non-immunized group, the difference between the two groups was significant (P <0.01)