Aquarium salt is a type of salt that is used in freshwater aquariums to promote fish health and treat mild cases of bacterial and fungal infections. It is made from evaporated sea salt and provides essential electrolytes that fish need to reach peak coloration and vitality. Aquarium salt helps osmoregulation of freshwater fish, which is the physiological process fish use to control the amount of salt and water in their bodies. It also keeps the slime coat of freshwater fish robust and healthy, promotes healthy gill function, reduces stress, and helps wounds heal. Salt essentially causes death by dehydration. By raising the salinity of the aquarium water, water is sucked out of the bacteria, fungus, or parasite as osmosis seeks to balance the salt concentration on each side of its membrane or skin. These tiny microorganisms dehydrate faster than the fish, and therefore the pathogens end up dying before their hosts do. Aquarium salt should be used with accurate measurements and careful usage, and it should only be added when doing water changes. Note that aquarium salt does not evaporate or get filtered out, so it should only be added in proportionate amounts when doing water changes.