NATURAL FISH TONIC. An all-natural sea salt that replace electrolytes which fish lose in times of stress, including potassium, sodium, chloride, calcium and magnesium. All of these are essential for the uptake of oxygen and the release of carbon dioxide and ammonia. * Made from evaporated sea water (not just a table salt or rock salt). * Helps eliminate the toxic effects of nitrite. * Improves gill function and reduces fish stress. Treats up to: 2,082L