Survey on the phytoplankton diversity were conducted at commercial fish farming pond in Bishnupur district of Manipur during 2017, 2018 and 2019 for their diversity and periodicity of occurrence. Phytoplankton are inseparable associates of the environment. There is a direct correlation of phytoplanktons to the physicochemical properties of water. Among the district of Manipur, Bishnupur is one of the leading fish producing districts. The present study was to understand the diversity and distribution pattern of microalgae in commercial fish farming pond. In the present study, 58 species of phytoplanktons belonging to 47 genera under 4 separate classes viz., Chlorophyceae (grass – green algae), Euglenophyceae (euglenoids), Bacillariophyceae (diatoms), Cyanophyceae (Blue-green algae) of 4 different divisions viz., Chlotophyta, Euglenophyta, Chrysophyta, Cyanophyta. Among the identified phytoplankton species Chlotophyceae (37.93%) formed the dominant group, followed by, Cyanophyceae (32.76%), Bacillariophyceae (24.14 %) and Euglenophyceae (5.36 %), respectively. The fluctuations in the physico-chemical parameters like pH. Temperature, DO, BOD, Turbidity, hardness, nitrate, phosphate and were also been monitored. The result provides a primary documentation of the phytoplankton community and its diversity and basic understanding hydrological variables in commercial fish farming ecosystem.