Among the major biodiversity hotspots of the world, Eastern Himalaya is known for its species richness and endemism located in the state of Arunachal Pradesh in north-east India. Apart from the terrestrial biodiversity, there are so many aquatic bio-resources like rivers, streams and lakes in Arunachal Pradesh. Gyakar Sinyik (Ganga Lake) is one such wetland located at Itanagar in the Papum Pare district. Preliminary study on the distribution of phytoplankton in the lake was studied during the year 2023.All the parameters were found to be within the permissible limit. A total of 41 genuscomprising of 57 species were observed during the study of phytoplanktons. They belong to 20family under 8 major classes. The number of sequences in order among different classes were Bacillariophyceae>Zygnematophyceae> Chlorophyceae>Euglenophyceae>Cyanophyceae>Dinophyceae>Chrysophyceae>Eumastigmatophyceae.ClassDinophyceae, Chrysophyceae and Eumastigmatophyceae were represented by one species each whereas Cyanophyceae with two species. The present study provides a valuable insight of the wetland in relation to water quality with the phytoplankton diversity.