Water temperature affects plants in many ways. A change of temperature alters metabolic activity and even affects aquatic ecosystems. From houseplants to aquatic plants, water temperature plays a part in growth and development Water temperature has a direct effect on the growth of aquatic plants. An unnatural introduction of warm water into a water body is called thermal pollution. Thermal pollution alters the population dynamics of aquatic plants. Also, some aquatic plants float to the surface in warm water. In this study we strongly explained that water temperature can fluctuate in every season which directly affect aquatic ecosystem .water temperature is taken from the month jan 16 to june 16 which ranges from28oC-42oC that shows large variation in plankton growth.