The dominant bacterial strain,designated as BCB01,was isolated from the kidney of enteric septicaemia of black carp Mylopharyngodon piceus.Artificial intraperitoneal injection with the bacterial suspensions to healthy black carp could reproduce the diseased symptoms as occurred in wild.Identification of the pathogen by Biolog system showed that the isolated causative pathogen BCB01 was Aeromonas hydrophila.According to their 16S rRNA gene sequence and molecular phylogenetic dendrogram,the strain BCB01 had close relationship to Aeromonas hydrophila with a similarity of 99%.The susceptibility test to antibiotics demonstrated that the isolate strain BCB01 was susceptible to most of the tested antibiotics,especially highly susceptible to 11 kinds of antibiotics,such as fortum,cefoxitin,cefobid and so on.