PolyGuard is the single most effective treatment to keep freshwater fish free of disease! Active ingredients: sulfathiazole (36%), malachite green (1.9%), nitrofurantoin (0.14%), nitrofural (0.14%), quinacrine dihydrochloride (0.27%). Inactive ingredients: excipients (61%) For use in freshwater or marine aquaria. Aquarium Use Only. Keep Away from Children. For ornamental fish only. Not for human consumption. Not to be used in conjunction with animals used for human consumption.