Studies to determine the feasibility of using ozone to disinfect seawater for use in controlled environment shrimp culture were run at the University of Arizona University of Sonora Environmental Shrimp Culture Station at Puerto Peñasco, Mexico. Ozone was injected into seawater containing known natural populations ofVibriospp. and known introduced populations ofFusarium solani. Total residual oxidant (TRO) concentrations and total viable plate counts for these pathogens were made during and post ozonization. TRO at a concentration of 2.6 mg/l was sufficient to kill greater than 99.9% of theVibriospp. present in the seawater within a 5-min exposure period. Greater than 99.9% of the introduced conidiospores ofF. solaniwere killed within 5 minutes after exposure to approximately 2.1 mg/l TRO.