The freshwater bath may help and it's suggested to do that with lions in Bob Fenner's book but it's not a cure all. I can't tell you if it's a shed or not, especially without seeing the fish. Also, I've never seen one do this, only read about it. Buying the QT
tank is a great idea. If you do the hypo treatment, you'll want to lower the salinity slow over a few days. I know there are several posts here somewhere on hypo treatment, I'll see what I can find. If you use copper, just use the directions on the bottle. Honestly, unless you have a refractometer, I would just do the copper treatment. Be sure to have plenty of sw
on hand for water changes. Placing the fish in a bare uncycled tank, you have to really watch the ammonia and nitrite levels. You'll need to do more water changes til the condition clears up as well. You may also want to buy a few pvc
elbows to place in the tank. This gives bacteria a place to grow as well as giving the fish some security.