The study was conducted for 6 weeks on February–April 2015, in the Laboratory of Center for Environmental Research (PPLH-IPB), Indonesia. This research used recirculation aquaponic system (RAS), where the water was not changed during the experiment. RAS consisted of nine aquariums (80 × 40 × 40 cm3) filled with 100 L of water for fish cultivation, tank (60 L) added biobal as bacteria surface media growth, and hydroponic subsystem for romaine lettuce cultivation. Each set of installation was equipped with a recirculation pump and aerator. The experiment consisted of three treatments with three replications, namely treatment without crops as a control (T1), treatment containing only romaine lettuce (T2), and treatment of romaine lettuce and inoculation with commercial bacteria (T3). The design of recirculation system can be seen in Fig. 1.