Abstract: Myxosporeans are microscopic and simple in morphology, mainly parasitize in fish. Some species can cause host disease even lead to death. Among them, the species of the family Myxidiidae Thélohan, 1892 exhibit the broadest range of hosts among all myxosporeans. They are typically coelozoic (rarely histozoic) parasites of marine and freshwater fishes (poikilothermal animals), and a few species are found in another poikilothermal animals (amphibians and reptiles) and homothermal animals (birds and mammals). The genus Myxidium Bütschli, 1882 with 230 described species, currently includes the most known species in the family Myxidiidae. The members of the genus Myxidium exhibit the following characteristics: their myxospores are spindle-shaped, straight, crescent, or even sigmoid with somewhat pointed ends; two pyriform polar capsules are located at both ends of the myxospores; the shell valves are smooth or striated; and the suture line bisects the myxospores. Myxidium spinibarba Chen et al., 2020 was first collected and described from the gall bladder of Spinibarbus sinensis Bleeker, 1871. Present study reported M. spinibarba again from Myxocyprinus asiaticus Bleeker, 1864. Myxocyprinus asiaticus belongs to the family Catostomidaeis, in which only one species has been reported from China. Myxocyprinus asiaticus is a kind of omnivorous benthic fish with important ornamental and edible value. To improve higher economic benefits, M. asiaticus and other fishes with different diets and habitat preferences are often mixed feeding. However, polyculture creates conditions for material exchanges between M. asiaticus and other fishes, and, it also enhances the transmission of parasites or pathogens.　　To study the host diversity for M. spinibarba and the species composition of myxosporean from M. asiaticus, we analyzed the morphometry characteristics and phylogenetic relationships of M. spinibarba from different hosts based on the morphological and molecular data. Myxosporeans were isolated and photographed from the gallbladder of different M. asiaticus in the same batch. Genomic DNA were extracted and 18S rDNA was amplified and sequenced. Myxospores were fusiform in frontal view, (12.6±0.6) μm (11.6—13.4 μm) long, (5.9±0.4) μm (5.1—6.9 μm) wide, and possessed distinctly longitudinal ridges. The two polar capsules were pear-shaped at the ends of the spore, with a length in (3.48±0.36) μm (2.63—4.22 μm) and a width of (2.83±0.26) μm (2.29—3.21 μm) with 4—5 turns polar filaments. The distance between two polar capsules was (3.66±0.29) μm (3.12—4.20 μm), and their openings were inclined towards the spore ends. These two sequences have the highest similarity with M. spinibarba (MH766654) parasitizing in S. sinensis (99.9%—100.0%). They shared 97.4%—97.7% identity with Zschokkella sp. (KM401441) from Labeo rohita Hamilton, 1822 and Myxidium sp. (MK913426) from Cranoglanis bouderius Richardson, 1846, respectively. Phylogenetic trees of the selected sequences were divided into branch A and B. Clade A was composed Myxidium and Zschokkella species from marine and freshwater fishes or amphibians. All species in clade B were collected from marine fish. Two strains in this study were located in branch A, where the strain (MT775466) and M. spinibarba (MH766654) were first clustered and then grouped with the strain (MT775467). The results of PCA showed that the two strains of this study (MT775466 and MT775467) and M. spinibarba (MH766654) overlapped on the scatter plot. The similarities and genetic distances of 18S rDNA sequences for three strains were 99.9%—100.0% and 0.000—0.001, respectively. Therefore, we conclude that these three strains from different hosts are the same species as M. spinibarba, with diverged molecular level, and that this is the first report of myxosporean in M. asiaticus.