Seachem Nourish is a comprehensive vitamin, amino acid, and trace element supplement developed to address nutritional requirements commonly associated with long term closed system housing of freshwater ornamental fish. Seachem Nourish contains potassium iodide in a heavy base of spirulina and chlorella. The nutrient iodine is essential for the biosynthesis of the thyroid hormones thyroxine and triiodothyronine. Both spirulina and chlorella contain a rich assortment of amino acids and vitamins. Seachem Nourish can be used on marine ornamental fish, however, it is specifically designed for freshwater fish.