In the present investigation, 140 species of phytoplankton belonging to 4 classes, viz., Cyanophyceae, Chlorophyceae, Bacillariophyceae and Euglenophyceae were recorded. They belonged to 46 genera and 11 orders. Among the phytoplankton population, Bacillariophyceae constituted 40%, followed by Chlorophyceae (30%), Cyanophyceae (20%) and Euglenophyceae (10%). The Bacillariophyceae was the dominant group of the phytoplankton population in all the stations followed by Chlorophyceae, Cyanophyceae and Euglenophyceae. The main reason for the high Bacillariophyceae population (40%) was rich nutrient and high temperature found in the tank. A total of 19 species belonging to 14 genera (Oscillatoria, Anabaena, Ankistrodesmus, Chlorella, Pediastrum, Scnedesmus, Tetraedron, Gomphonema, Navicula, Nitzschia, Synedra, Euglena, Phacus and Coelastrum) were recorded in all the stations. The maximum species was recorded in S-3 and S-4 due to the pollution status in this station.