Sustainable aquaculture focuses on environmentally friendly production to meet current demands for food production without depleting natural resource s. Biofloc technology (BFT) system supports this goal by minimizing or eliminating water exchange. T his study evaluates the mass balance of Nile tilapia reared in BFT system using total carbon (TC), total nitrogen (TN), and total phosphorus (TP) . To calculate the mass balance of TC, TN, and TP , the input of nutrients was considered from the supply water, the initial biomass of fish, and the feed-diet during the experimental period of 70 days. The output of nutrients was determined based on the amounts retained within the final fish biomass and those present in the effluent. The mass balance analysis revealed a high level of nutrient retention within the fish biomass, with minimal nutrient losses to the aquatic environment.