Objective To observe and identify the microorganism isolated from diseased and dead Ctenogobius gymnauchen cultured in seawater near the Daya Bay of south China sea. Methods GDLAMI-1210 strain was isolated from the diseased Ctenogobius gymnauchen (Bleeker). We applied physiological and biochemical characteristics in the bacterial classification. In order to confirm the results, we amplified a 1438 bp sequence of GDLAMI-1210's 16 S rRNA(HM 362434)and compared with other sequence in GenBank, and followed by artificial infection. Results The GDLAMI-1210 strain was Gram-negative and in a shape of short rod with single polar flagellum. The homology analysis and phylogenetic study showed that the 16 S rRNA sequence of GDLAMI-1210 has the highest similarity to Vibrio sp. espec Vibrio vulnificus, showing 99% identity. Conclusions To our knowledge, this is the first report that the causative pathogen, Vibrio sp, leads to the mortality of Ctenogobius gymnauchen (Bleeker).