API Aquarium Salt provides essential electrolytes freshwater fish need to reach peak coloration and vitality. API Aquarium Salt improves gill function, reduces stress, facilitates osmoregulation and promotes disease recovery. Freshwater fish actively maintain a natural balance of electrolytes in their body fluids and electrolytes are essential for the uptake of oxygen and the release of carbon dioxide and ammonia through their gills. A lack of electrolytes may cause serious health problems so API Aquarium Salt is made from evaporated sea water and provides these essential electrolytes fish need for optimum health. Use the API Aquarium Salt when setting up a freshwater aquarium or fish bow, changing water or treating fish disease.