Hi, we asked at the LFS near us when we thought it was gill flukes. The man told us to put in a 1/4 cup of aquarium salt per 5 litres of water (don't know how many gallons that converts to). He said to do it for 8-10 minutes, once a day for three days. If that didn't work he was going to look at a gill scraping for us.
It seemed like a lot of salt to me when we did it, but by day two he had stopped breathing so heavily and is now completely back to normal.
Before I did a bath though, I would look at things like a possible build-up in ammonia and nitrite etc. and just generally check that all your water levels are stable and where they should be.