A method for reducing parasites in aquatic animals is provided. The method includes reducing a plurality of parasites infecting an aquatic animal by administrating to the aquatic animal a compound comprising propyl propane thiosulfonate (PTSO) having the formula R—SOa-S—R, where R represents n-propyl group (—CH2—CH2—CH3) and a is 2. In yet a different embodiment, a method for reducing a plurality of parasites infecting an aquatic animal includes administrating to the aquatic animal a compound comprising and propyl propane thiosulfinate (PTS) having the formula R—SOa-S—R, where R represents n-propyl group (—CH2—CH2—CH3) and a is 1. In even yet another embodiment, a method for preventing a plurality of parasites in aquatic animals is provided and includes administrating to an aquatic animal a compound including PTS. In a different embodiment, a method for preventing a plurality of parasites in aquatic animals is provided and includes administrating to an aquatic animal a compound including PTSO.
