Abstract: The healthy Pelteobagrus fulvidraco were artificially infected with Yersinia enterocolitica (Y.enterocolitica) strain GM2402 by intraperitoneal injection to test the median lethal concentration (LC₅₀).The histology changes of Pelteobagrus fulvidraco were studied by histopathological methods.These results showed that the challenged fish indicated abdomen swelling, pectoral fin and ventral fin bleeding, swelling and bleeding on anus after intraperitoneal injection.The LC₅₀ value of Y.enterocolitica in Pelteobagrus fulvidraco was 3.0×10^6.2 CFU/mL.The main histopathological changes of organs indicated that swelling and degeneration of hepatocyte were observed in the liver.In the kidney, swelling and degeneration were showed in renal tubule epithelial cell.A large number of erythrocyte emerged in spleen. Gill lamella showed mild congestion and swollen.The ultrastructures indicated that there were distinct changes in liver and intestine, especially in mitochondria.The cristaes of mitochondria were disordered and disappeared. In conclusion, Y.enterocolitica strain GM2402 was pathogenic to Pelteobagrus fulvidraco.

Key words: Pelteobagrus fulvidraco; Yersinia enterocolitica; histopathology