The paper presents data on the state of populations of species of the genus Daphnia in the ecosystems of small lakes in the forest-steppe zone of the south-west of Western Siberia, in which they are the highest trophic link. The research was conducted in 2017 on the territory of the Kurgan region. In total, 5 lakes (Lysanovo, Dolgoe, Golovka, Second Mogilnoye, Krutoyar) located between 66°30’ and 67°00 ‘ were studied.d. and 55°00’ and 55°30 ‘ s. The studied lakes are typical for the forest-steppe zone of Western Siberia. According to the chemical composition, the lake waters of the studied limnoecosystems can be attributed to the bicarbonate and chloride classes, the sodium group. 5 species of the genus Daphnia were found in the reservoirs: Daphnia (Daphnia) - D.(D.) pulex, D.(D.) obtusa, D.(D.) longispina, D.(D.) galeata, and Daphnia (Ctenodaphnia)- D. (C.) magna. Populations of D. (D.) pulex are found in all the studied reservoirs. The maximum density and biomass of crustaceans of this species is noted in Lake Mogilnoye of 51 thousand individuals/m² and 3.62 g/m², respectively. The minimum, in the lake Dolgoe – 3.8 thousand individuals/m² and 0.019 g/m². Of the other species, D. (C.) magna is most common-in three reservoirs. At the same time, there is a significant variability in the population density from 0.478 thousand. individuals/m² (Lake Krutoyar) up to 9,864 thousand. individuals/ m² (lake Dolgoe). D. (D.) longispina is found in two lakes – the Golovka (25,230 thousand. individuals/m²) and Krutoyar (6,428 thous. individuals/m²). The lowest occurrence is typical for D. (D.) obtusa (Lake Golovka) and D. (D.) galeata (Lake Lysanovo). The greatest species diversity of the genus Daphnia was observed in Lake Golovka (3 species) and Krutoyar (3 species). It is concluded that the studied limnoecosystems are characteristic daphnia reservoirs with the dominance of one or two species from the genus Daphnia.