The materials for 2003-2018 on the biological state of sazan of the eastern part of the Taganrog Bay and the Don River delta were summarized. It has been shown that the catches of sazan in the study area consisted of more than half of the fish of younger age groups, the length of which was less than the commercial measure. The ratio of linear and weight growth of sazan is shifting towards a decrease in the mass of one-dimensional specimen, which is indirect evidence of the deterioration of the natural living conditions of semi-migratory fish. In 2019, the carp parasite fauna was represented by 7 species related to monogenes - 2 species, cestodes - 3 species, nematodes - 1 species, crustaceans - 1. The state of the sazan population needs further research.
WATER TOXICITY OF THE DON RIVER MOUTH AREA BY BIOASSAY BATTERY DATA