Seachem Nourish is a top of the line liquid supplement designed specifically to aid the nutritional requirements of freshwater and ornamental fish housed in long-term closed aquarium systems. The solution provides an additional boost of necessary vitamins, amino acids and trace elements that help to prevent diseases caused by deficiency-thyroid ailments as well as contributing to proper growth and development. As well, Seachem Nourish contains valuable potassium iodide in a base of spirulina and chlorella (ingredients that contain a rich assortment of amino acids and vitamins). The nutrient iodine enhances water quality and is essential for the biosynthesis of the vital thyroid hormones thyroxine and triiodothyronine in fish. The solution can be used on saltwater fish but it is designed specifically for freshwater environments. Comes in a 500 ml container. Directions: Shake the solution well before using. For the best results, it is advised to soak the desired fish food in one capful of Nourish daily.