Epsom salt is synonymous(same as) with aquarium salt...1 tablespoon of whatever salt per 5 gallons.
Some fish, or aquarium pets are sensitive to salt. So read up. "Iodized" table salt is BAD, non iodized can be used the same as others.
Iodized will be labeled boldly, but just read all the words and compare the two at the store and you will easily see the difference.
Salt is a fix all so to speak, and a good alternative to many chems and meds.
It promotes fin regeneration, slime coat, soothes the gills in times of high stress or after allot of particles get stirred up in the tank.