Hematological parameters and parasite fauna of Amur sleeper Perccottus glenii in a single-species ichthyocenosis of a small urban resvoir

The article presents the results of hematological and parasitological studies of Amur sleeper Perccottus glenii of a small reservoir of artificial origin located in the vicinity of Perm. In this reservoir, Amur sleeper is the only representative of the ichthyofauna. The collection of material was carried out in the spring-summer period of 2019. A total of 55 specimens of Amur sleeper were studied (30 specimens on May 8 and 25 specimens on July 12). Significant differences were found in the majority of quantitative indicators of fish blood cells in the spring and summer periods: in summer, the number of hematopoietic cells is higher (except for lymphocytes and monocytes), and in general, the content of mature leukocytes in the blood microliter in summer is lower. The parasite fauna of Amur sleeper in the studied reservoir is extremely impoverished and is represented by the infusoria Trichodina nigra, cestode Nippotaenia mogurndae and nematodes, the latter were not recorded in Amur sleeper in this reservoir previously. The relationship between hematological parameters and the extent of parasite invasion was revealed: in more infected fish the number of immature erythrocytes, protoleukocytes, as well as neutrophils and eosinophils is significantly higher. The large numbers of Amur sleeper in the studied reservoir, the absence of developmental anomalies in all the studied specimens, and the low proportion of fish with blood cell pathologies indicate the relative well-being of the studied part of the Amur sleeper population.