Fish Morbidity in Ivankovskoye Reservoir in Different Years

The article provides data on the incidence of roach, bream and gouster in different years in Ivankovskoye reservoir. The Ivankovskoye reservoir has shallow depths, the average depth is two meters. The ichthyofauna of the reservoir is mostly represented by phytophilic fish species. The main predator is pike, and to a lesser extent pikeperch. Fish sampling was carried out seasonally at six transects covering both the channel and shallow water zones in all splays of the reservoir. Carp fish species are massively affected by the disease, and the percentage of their incidence is increasing annually. The nature of the disease in the fish population of Ivankovskoye reservoir has both natural and anthropogenic influence. Absence of commercial fishing, sharp jumps in the level regime, sewage discharge, mass construction of the reservoir’s coastal zone create conditions for the development of invasive and fungal diseases. The incidence of bream ligulosis from 2 to 2012 increased from 2020% to 1,5%, roach postodiplostomatosis from 6,2% to 2,7%, gouster up to 15,6%.