Nile Tilapia and romaine lettuce can grow well together in aquaponic system in this study. Romaine lettuce growth in T2 (nile tilapia and romaine lettuce) and T3 (nile tilapia. romaine lettuce, and addition of bacteria) was well recorded by color of fresh green leaves, and there were no signs of nutritional deficiency. Romaine lettuce could utilize nutrient originating from fish culture. This nutrient was a result of decomposition of fish excreta and uneaten food. Best growth of nile tilapia was shown by T3 in terms of FCR, proportional to better water quality in this treatment. Thus, romaine lettuce could, to some extent, purify water quality of fish culture media to be reused in the fish culture. Aquaponic system (nile tilapia and romaine lettuce) without water exchange can maintain the quality of the water suitable for fish and plant growth, without having to replace the water regularly like in conventional cultivation system. Further research on optimization of the number of plant incorporated in fish culture in aquaponic system is required.