Skills and knowledge must also be based on good practice. For example, antibiotics are mixed into the fish feed and fed to the fish several times every day over, for example, 7 or 10 days. The concentration of antibiotics must be sufficient to kill the bacteria, and the prescribed concentration of medication and the length of the treatment must be carefully followed, even if the fish stop dying during the treatment. If treatment is stopped before the prescribed treatment period, there is a high risk that the infection will start all over again. Treatment with antibiotics in a recirculation system will have a small effect on the bacteria in the biofilter. However, the concentration of antibiotics in the water, compared to that inside the fish being treated with medicated feed, is relatively low, and the effect on bacteria in the biofilter will be much lower. In any case, one should carefully monitor the water quality parameters for any changes because they may indicate an effect on the biofilter. Adjustment of the feeding rate, use of more new water or changing the flow of water in the system may be necessary. Several antibiotics can be used, such as sulfadiazine, trimethoprim or oxolinic acid according to the prescription by the local veterinarian.

Chemicals usage by some farmers is unnecessary and can cause more problems than intended to solve. Pesticides are banned for use in aquaculture. In many countries there are few therapeutants approved for application for fish to be consumed by humans. Some farmers choose to apply antibiotics in a preventative manner such that disease resistant bacteria can be fostered. Chemicals are to be used sparingly or eliminated completely from production. Most tilapia grow-out farming requires no chemical applications.