During the past years more than 30 bacterial isolates of carp erythrodermatitis (CE) agent were obtained from ulcers of carp originating from various Hungarian fish farms. Successful isolations were primarily carried out from the peripheral area of ulcers on blood agar. Infected carp showed characteristic dermatitis 5-6 days after scarification. There were either ulcers, or small sized papulas. The pathogen could be easily reisolated from the lesions, and had almost identical features in the bacteriological procedures. Thus, these CE agents seemed to belong to Aeromonas genus of Vibrionaceae. More exactly, their bacteriological properties mainly corresponded to those of Aeromonas salmonicida but slightly different from its subspecies.