The extent of invasion by postodiplostomum cuticola metacercariae of fish caught in the reservoirs of the chuvash republic in the summer of 2024

Abstracts. Fish caught by fishermen, in most cases, are not subjected to veterinary and sanitary examination and their safety is not controlled by anyone. Given the fact that there are many fish diseases that at least reduce the quality of fish products, consumers of fish products, due to ignorance, put their health at risk. The aim of the work is to analyze the extent of invasion by metacercariae of the digenetic fluke Postodiplostomum cuticola of fish living in the reservoirs of the Chuvash Republic. The study was conducted between June and September 2024. The objects of the study were 10 reservoirs of the Chuvash Republic and fish caught on them of different species composition in the amount of 315 specimens. It was found that only 3 reservoirs located near the villages of Bateevo, Starye Shchelkan and Novoe Muratovo of the Urmar Municipal District of the Chuvash Republic turned out to be safe for postdiploidomiasis, while the rest of the fishermen catch fish affected by metacercariae. The extent of the fish invasion depended on the species, so in the waters of the Musirma Riverdam in the vicinity of the village of Musirma and the dam of the Sredny Anish River in the vicinity of the village of Karak-Sirma in the Urmar Municipal district, only perches were sick with postdiploidomiasis, and all caught specimens of roach were free of metacercariae. In addition, it was found that the extent of the invasion differed greatly between different, closely located areas of the water area of the same reservoir, such as on a pond near the village of Shihabylovo in the Urmar municipal district and the dam of the Anish River in the vicinity of the village of Staroe Akhperdino in the Kanash municipal district. Among the 315 fish caught, 100 were affected by metacercariae, of which 30 were found unfit for food. In general, it can be unambiguously concluded that the extent of invasion has a direct relationship with the characteristics of the reservoir, such as the nature of the bottom, depth, the presence of aquatic vegetation and fish-eating birds.