Abstract: Vibrio vulnificus in fish is one of the widespread and serious bacterial diseases. In June 2019, the diseased clown anemone fish（Amphiprion percula）in Tianjin certain aquaculture farm mainly experienced clinical symptoms such as abdominal bleeding, intestinal enlargement, and fluid accumulation in the body, leading to serious illness and death. In this study, a bacterial strain named VA-1 was isolated from diseased A. percula. Through morphological observation, physiological and biochemical characteristics, 16S rDNA gene sequencing, artificial infection test and drug sensitivity tests, the results showed that VA-1 was Gram-negative bacteria and positive for galactose, glucose, cellobiose, maltose, turanose, fructose and so on. Blast retrieval showed that the similarity between VA-1 strain 16S rDNA gene sequence and Vibrio vulnificus（MH244242.1）was 100%. Phylogenetic tree analysis showed that VA-1 strain was most closely related to Vibrio vulnificus（MH244242.1）, and they were naturally clustered into one branch, so the strain was finally identified as Vibrio vulnificus. The results of drug sensitivity test showed that the strain was sensitive to cefalexin, azithromycin, levofloxacin and other drugs, but resistant to tetracycline and vancomycin. Half of the lethal dose（LD₅₀）of healthy Barchydanio rerio var was 1.33×10⁵ cfu/mL. The above results indicate that this strain has strong pathogenicity to fish, laying a foundation for the diagnosis and treatment of V. vulnificus in A. percula.

Key words: Amphiprion percula, Vibrio vulnificus, separation and identification, drug sensitivity