The Ganga river originates from the ice cave of Gaumukh (33⁰ 55’N, 79⁰07E) at Gangotri glacier of Western Himalaya, about an elevation of 4100 meters. The population dynamics of zooplankton diversity in Ganga River and its tributaries at Rishikesh was subjected to check the population dynamics of zooplankton diversity from September 2017 to August 2018. The sample was analysed qualitatively as well as quantitatively for distribution of zooplankton. During the present experimental study 15 species of zooplankton of which 5 species of Cladocerans, 4 species of Copepods, 3 species of Protozoa and 3 species of Rotifers were recorded. Shannon Weiner Diversity (H’) was ranged from 2.59 to 2.682, evenness (J’) was 0.8888 to 0.9746 and Simpson diversity was ranged from 0.9184 to 0.9299.