"PolyGuard is the single most effective medication to keep freshwater fish free of disease! It is an effective treatment and safeguard against all prevalent bacterial, fungal, and parasitic diseases of exotic fish. For use in freshwater or marine aquaria. PolyGuard is recommended for the treatment of certain diseases in marine and freshwater fish only. It IS NOT recommended for treating any style aquarium containing invertebrates, corals, crustaceans, or elasmobranchs (sharks and rays). "