WaterLife Octozin (21) is a highly effective, broad-spectrum treatment designed to combat protozoan parasites in both freshwater and marine aquariums. Specifically formulated for the treatment of Oodinium (marine velvet), Trichodina, Costia, and other external protozoan infections, Octozin helps to control and eliminate these common parasites that affect fish. Its gentle yet powerful formula is suitable for use with a wide variety of aquatic species, ensuring your fish recover quickly without compromising the health of your aquarium's plants, filtration, or other inhabitants.