This survey was conducted on 775 specimens of Acipenser gueldnstaedtii. A number of 27 specimens were identified from viewpoint of external lesions and samples were studied for bacterial agent's isolations.It was determined the most content of lesions was related to scutes with abundance of 81.48% after that, skin (37.04%) and fin (7.4%), respectively. The most lesions were in ventral skin and scute. In bacteriological experiments, Genera of Aeromonas, Acinetobacter, Pseudomona, Enterobacter and Proteus were detected. Acinetobacter (42.11%) had the most abundant and proteus and Enterobacter (each one 5.6%) the least abundant from total bacteria. Existence of lesion in ventral surface can be because of benthivorous feed behavior. With regards to a relation between isolated bacteria in this study and known species in water, health management is mandatory to preserve water quality, prevention of increase of organic load and providing of suitable density and reduction of handling in order to control of bacterial agents.