The intestinal microbiota of fish plays a vital role in the host.Photobacterium damselae subsp.damselae(PDD)is a common pathogenic microbe in cultured silver pomfret(Pampus argenteus),often cause massive mortality.However,the impact of PDD infection on the intestinal microbiota of P.argenteus during the development of PDD disease is unclear.In this study,P.argenteus was infected with PDD by intramuscular injection,and the midgut and hindgut of healthy and diseased P.argenteus were collected at 24 h and 72 h for 16S rRNA gene amplicon sequencing.The results showed that PDD proliferated and dominated in the intestinal tract of P.argenteus after infection,reducing the relative abundance of other microbial groups,disrupting the normal balance of the intestinal microbiota,and causing a disorder in the composition of the microbial community in the intestinal tract of P.argenteus.