salt is very effective at killing FRESHWATER PARASITES it can also kill your fish , bacteria nuewts, frogs, tads, dragfly nymph, and plants.
Ulcers are a result of ph imballance . chemicals in the water like chlorine, chlomine, or any other high or too low levels . when your fish has a ulcer / often red blotch on it's side looks like a fresh burn , thats because it is a type of burn and to put a fresh water fish with a burn into a salt is cruel even at a low dose. you can use potasium pergonite as a dusting powder on a bacterial fuzz or ulcer this is painful to the fish but it will kill any parasite or bad bacteria or fungus.
there are also spray bandaids and many other alternatives . Knowing the cause is key a microscope and a scale and a good book become key.