| Half-smooth tongue sole (Cynoglossus semilaevis Günther) is one marine fish speciesnative to northern China off shore areas. In this paper, typical disease samples are selected forhistopathology and identification of pathogens research in cultured half-smooth tongue soleby using paraffin section technique, microorganism cultivating, artificial infections, pathogenphysiological and biochemical characteristics and16S rRNA methods respectively. Theresults of these studies will enrich the data of flatfish diseases research, and provide thefundamental works for constructing half-smooth tongue sole disease control and preventiontechniques system. All the results of this paper are as follows:1．Isolation, identification of the pathogenDominant bacteria were isolated from diseased Cynoglossus semilaevis Günther, andhave strong pathogenicity to Cynoglossus semilaevis Günther by artificial challenge.Themolecular identification were also conducted,the sequenced16S rRNA gene of strain is1,603bp inlength.Blasting of16S rRNA in NCBI showed high homogeneity between theisolates and Vibrio sp. about99%.From GenBank database.The results showed that theidentified strains belonged to Vibrio parahaemolyticus of Vibrio based on their phenotypicand molecular characteristics. Drug resistance of isolates to50antimicrobial agents wasdetected, and the results showed that isolates were high sensitive to43agents includingaztreonam, and also sensitive to lincomycin, furthermore they were resistantto6agentsincluding penicillin G.2．Histopathology of cultured half-smooth tongue sole typical diseasesAs the typical diseases, the fish associated with ascites symptom are chosen forhistopathology analysis. The results reveal that most organs of ascites fish exhibit varyingorgan lesion. The major organs pathological changes of diseased fish include heart fiberspyknosis and focal ulceration，tissues necrosis and ulcer in the hepatopancreas and kidney，detachment of mucosal epithelium and lamina propria in intestinr tract.Surmising from theresults, multiple organ tissues damage and metabolic dysfunction or loss, this may be theultimate cause of death in diseased fish. |
