Parasitological inspection of some representatives of the Perch and Pike families of the Lower Volga basin

The safety of fish for human consumption requires veterinary and sanitary expertise, especially in terms of parasitic purity, given the tense epizootic situation of parasitic diseases in the lower Volga region. Predatory fish species of the Perch family (walleye (Sander lucioperca), perch (Perca fluviatilis)) and Pike (pike (Esox lucius)) living in open reservoirs of the Astrakhan region have been studied. From 2023 to 2025, 57 specimens were examined. Techniques of parallel incisions, examination of muscle tissue for lumen, and compressor analysis were used. During the study period, a wide range of parasitic organisms was identified, including trematodes (Apophallus (=Rossicotrema) donicum, Tylodelphys clavata, Diplostomum sp., Paracoenogonimus ovatus, Rhipidocotyle campanula) and nematodes (Eustrongylides excisus, Anisakis sp., and Raphidascaris sp.). The characteristic locations of individual parasite species have been identified: Rossicotrema donicum was mainly fixed on the fins of representatives of the genus Diplostomum sp. and Tylodelphys clavata – in the vitreous body of the eye, Paracoenogonimus ovatus – in the dorsal musculature. Nematodes (Eustrongylides excisus, Anisakis sp., Raphidascaris sp.) have been found in the body cavity, muscle tissue, and intestines. Special attention is paid to the analysis of mixinvasions, which often cause more severe damage to the host organism. It has been established that the most common mixinvasion in perch and walleye is a combination of R. donicum + + P. ovatus + E. excisus. The species diversity and frequency of mixinvasions were maximal in perch. A high percentage of Rossicotrema donicum infection was observed in 100% of the studied specimens of walleye and perch, Eustrongylides excisus in 17% of walleye, 25% of pike and 50% of perch. The data obtained confirm the need for regular veterinary and sanitary inspection in terms of parasitological control of fish species in the region to ensure the biological safety of fish food products.