rae64 said:Salt used to be highly recommended to treat illnesses. It causes irritation, therefore resulting in the fish over-producing their slime coat. But, "irritation" being the operative word, this causes discomfort for the fish. It is not typically recommended anymore. Some fish like certain puffers are brackish fish, and need salt in their water to survive. I do believe that this is marine salt though, not aquarium salt. This is because they naturally live in places where rivers and the ocean meet, creating a sightly salty (but not totally salty) environment. I would not suggest adding any salt to your tank. It will particularly irritate your sensitive corys.