The use of ozone in a recirculating aquacultural production system on a commercial scale was investigated. ozonation was responsible for statistically significant differences in all test parameters, including: heterotrophic plate count, total coliforms, fecal coliforms, total solids, and total volatile solids. Results indicated ozone had a significantly positive effect in the recirculating aquacultural production system. Further study is recommended, however, to better understand the effects of ozone and to justify economically the use of ozone in commercial systems.