SulfaPlex (formerly Sulfathiazole) is an effective and safe treatment for many bacterial, fungal and protozoan infestations in the aquarium. Easily removed with carbon and does not impair nitrification. SulfaPlex 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).