"i use doc wellfish's aquarium salt in all my freshwater tanks. it is excellent in helping with gill function,replacing electrolytes and does help prevent against disease with proper water quality and the usual maintenance and care for your fish. of course even with preventatives we all sometimes get sick, but i have never had a problem with any of my fish that i use this product with. it can be added straight to the tank with every partial water change, it can also be used in higher doses as a salt bath for ill fish.(of course always follow directions and becareful not to overdose) it really does a wonderful job. i recommend it to anyone who is planning on purchasing a tank or kit, or anyone that already has fish and wants to improve their health and reduce chances of illness and yes it can even be used with bettas and goldfish."