Аннотация:Eutrophication of Water Bodies and Control of This Processwith the Use of Zooplankton and Planktophage FishT. N. Gerasimova* and A. P. Sadchikovb**a Institute of Water Problems, Russian Academy of Sciences, Moscow, 119333 Russiab International Research Centre for Biochemical Technology, Lomonosov Moscow State University, Moscow, 119991Russia*e-mail: gerasiming@gmail.com; **e-mail:aquaecotox@yandex.ruReceived July 1, 2024; revised July 7, 2024; accepted July 10, 2024Abstract—The study was carried out in a number of small water bodies within the boundaries of Moscow. In thesewater bodies, regular and mass blooming of cyanobacteria and green algae was recorded. Due to the long-termrepeated spawning during the summer, juvenile fish of various sizes were constantly present in the pond. Theymostly consume large-size zooplankton. Because of this, the dimensional structure of the population shifts towardssmaller species. Simocephalus vetulus was recorded in the water body only once (July, 24). Its number was as smallas 0.1 spec/L. After that, up to the end of the study, it was not observed in the pond, although it developed verywell in an experimental ecosystem (into which it had entered from the water body). In an isolated flow-throughecosystem (in the absence of fish), the number of S. vetulus in August reached about 9 thousand spec/L. It was notobserved in the pond because of its grazing by fish.Keywords: eutrophic water body, cyanobacteria, green algae, pond ichthyofauna, zooplankton