Commercial bacteria (Nitrobacter sp. and Nitrosomonas sp. with a density of 106 CFU/mL) were added to T3 as much as 32 mL per week according to the instructions on the package. The addition of the bacteria into this system is intended to supply organic substances decomposing bacteria. The addition of the bacteria was expected to increase nitrification process, expected to reduce nitrogen content, especially in the form of NH3 toxic to fish, and provided dissolved nutrients for plants.