I still can't find it. I found it while doing bloat research but can't find it now. Basically it says that aquarium salt is an irritant to fresh water fish. Which is what causes them to produce more slime. But aquarium also dehydrates fish and can cause irreparable damage to their kidneys. Freshwater fish natural take in salt constantly because in the wild it is not present in large quantity. ( this applies to true freshwater fish or "sweet water" fish) So they automatically start absorbing the salt which in turn dehydrates them as they try to expel it. This can be beneficial for some diseases and salt can treat ich. But for general use it shouldn't be used. For damage like you described I would use melafix or just let him recover on his own.
