The effects of nutrients on growth of Thalassiosira fluviatilis were found out by incubating the culture for a period of one week in complete darkness and exposing it to light of 3000 lux intensity continuously. Complete darkness did not favour much growth though the nutrients are supplied as in F/2 medium level. When the culture exposed to light after dark period, maximum growth was observed at full enrichment level. Nitrogen and phosphorous had been found to be very effective than other nutrients in enhancing or declining the growth of T. fluviatilis.