Abstract: The introduction of largemouth bass (Micropterus salmoides) to China as a cultured fish from North America has been associated with increased mortality, primarily caused by monogeneans. These pathogenic monogeneans parasitize the gills of the largemouth bass, prompting an investigation into the monogenetic species composition and infection status on the cultured bass to assess the invasive risk in Hubei Province. Co-introduced parasite species were identified as Onchocleidus dispar and Clavunculus bursatus based on morphological characteristics. In the fishery in Daye, Hubei, O. dispar and C. bursatus were found with the prevalence rates of 12.90% and 1.08%, and mean abundance of 0.14 and 0.02, respectively. At the Xinzhou fishery, M. salmoides exhibited infection with O. dispar, showing prevalence and mean abundance rates of 22.22% and 2.14, respectively. Following the largemouth bass introduction to China, there has been a noticeable decrease in the species richness of monogeneans compared to their native range. O. dispar has become established on farmed largemouth bass in Wuhan, situated in the middle floodplain of the Yangtze River.