A study was conducted to analyze the makeup of the rotifera community in terms of both quantity and quality. The study took place over four seasons at two locations on the Tigris River, both before and after the construction of Al-Kut's Barrage. The study period spanned from January to December 2023, during which a total of 48 taxonomic units of rotifera were discovered. The overall population density of the Rotifera at the initial location prior to Al-Kut's Barrage varied between the peak value of 10509.9 individuals/m3 in the spring and the minimum value of 2621.1 individuals/m3 in the winter. The second location downstream of Al-Kut's Barrage had a peak density of 5198.8 persons per cubic meter during spring, while the lowest density of 1088.3 individuals per cubic meter was seen during winter. The study examined the indicators of relative abundance and the Shannon-Wienercoefficient of biological diversity. The values observed ranged from 2.198 to 6542 bits per individual. The index of species appearance homogeneity ranged from 0.67 to 0.85, and the index of species abundance ranged from 5.25 to 7.89. The decline in the population of Rotifera during winter is attributed to the adverse impact of cold temperatures, which hampers the restricted growth of the species. During the winter season, there is a reduction in illumination and phytoplankton, resulting in a fall in food availability. This shortage of food is responsible for the decline in Rotifera populations.