Fritz A+ Aquarium Salt helps keep freshwater fish healthy. Fritz A+ Aquarium Salt is an all-natural salt that provides the essential electrolytes freshwater fish need for the uptake of oxygen and release of carbon dioxide and ammonia through the gills. Without electrolytes, fish might face serious health problems. Fritz A+ Aquarium Salt should only be added to reduce stress during new aquarium setup and water changes or to promote disease recovery when solving specific fish health issues.