Aquarium Salt provides essential electrolytes freshwater fish need to reach peak coloration and vitality. Electrolytes are essential for the uptake of oxygen and the release of carbon dioxide and ammonia. The lack of electrolytes may cause serious health problems. API Aquarium Salt, made form evaporated sea water, provides the essential electrolytes fish need to thrive in an aquarium. Use when setting up a freshwater aquarium or fish bowl, changing water and treating fish disease. Treats up to 107 U.S. gallons.