API Aquarium Salt, made from evaporated sea salt, is a must-have for your aquarium! Aquarium salt promotes fish health by improving gill function, making it easier for fish to breathe. It also provides essential electrolytes that fish need to reach peak coloration and vitality. These electrolytes may be lost each time you perform a partial water change, and will need to be replenished with API Aquarium Salt. Use API Aquarium Salt in freshwater aquarium tanks when starting a new aquarium, and any time you perform a water change. Care should be taken when using salt in aquariums with live plants, as some plants may be sensitive.