The green seaweed Ulva reticulata used as co-culture species for monitoring the changes in toxic nitrogenous wastes in the shrimp culture system was found to efficiently remove ammonical nitrogen from 249.5 to 17.39 pmol nitrogen11 (94%). The nitrate nitrogen reduced from 28.39 to 24.21 pmol nitrogen 11 (5%) and nitrite nitrogen from 14.51 to 9.03 pmol nitrogen11 (22 %). The removal of total nitrogen from the aquaculture system was found to be 45 % when treated with seaweed. The concentration of toxic nitrogenous wastes was found to be always at a lower level in the integrated system when compared to the monoculture system. Seaweeds of economical importance can be used in aquaculture system to improve water quality and generate revenue for the industry.