从北京某渔场发病锦鲤中分离出 8株细菌。经形态学、生化特性鉴定及凝集试验 ,证明其中 3株为嗜水气单胞菌。通过溶血试验、脱脂奶琼脂平板法、Dot_ELISA法及动物试验 ,显示这 3株菌均能产生溶血毒素和胞外蛋白酶 ,并能致死小鼠。药敏试验表明它们对常用抗生素呈不同程度的耐药性 Eight strains of bacteria were isolated from koi in a fishery in Beijing. The morphological, biochemical characteristics and agglutination test showed that 3 of them were Aeromonas hydrophila. Through hemolysis test, skim milk agar plate method, Dot_ ELISA and animal experiments, all three strains could produce hemolysin and extracellular protease, and could kill mice. Susceptibility tests show that they have different levels of resistance to commonly used antibiotics