Four strains of domain bacteria were isolated from the liver of Hybrid Sturgeons,Huso huso(♀)×Acipenser ruthenu (♂) and ascites of Kaluga Sturgeons,H. dauricus.Their pathogenity was determined by artificial infection test.The pathogenic strain was identified by ATB bacteria identification instrument,and its growth characteristics was also studied.The results indicated that,strain XL₂-T was pathogenic to Hybrid Sturgeons and Kaluga Sturgeons,and was identified as Aeromonas punctata caviae.Its growth curve in the sterile liquid culture medium was as follows:lag phase 0-1.5 h, log phase 1.5-28 h,stationary phase 28-32 h, and decline phase after 32 h.Its best growth conditions were 25-30℃ and pH 7,and it could grow in culture medium with 0-10% NaCl and 0-40 μg/ml sarafloxacin,but NaCl and sarafloxacin had some inhibitory effects on its growth.