The current study is the first to record that larvae of the nematode Echinuria uncinata were found in Daphnia magna species in the Fergana Valley, Uzbekistan. Zooplankton specimens of Daphina magna were collected using hydrobiological methods from the Sariqamish Lake shoreline and the adjacent pond areas (9 spots) in spring and autumn, 2019-2020. It was noticed that 11.5% of the samples were infected by nematode larvae. To detect the impact of infection on the intermediate host, samples were subjected to morphological and morphometric parameters.[A1]  In addition, the development of larvae was addressed in the intermediate host, D. Magna. The infected nematode eggs were supplied with food and their development was studied at different temperatures. After 24- 26 days, at low temperatures (1-15°C), the fourth invasive stage was reached. While, on days 9-10 of the experimental period, and at 20-22°C, the invasive stage was recorded. Meanwhile, on days 8-9 days at a relatively high temperature of 24-26° C[A2], the same stage was noted.