A salt bath for ich does little good for the fish. The salt will not kill the parasites on the fish. Salt will kill the ich tomites (free swimming stage of ich). The tomites will be found in the aquarium water. Add salt to the aquarium water to cure ich. Don't dip the fish in a salt bath.
X2 increasing the temp to the 80s 90's will also help.. it causes the parasite to go threw it's cystic stage faster and often times kill the parasite due to it's intolerance to extreame temps...
side note imho/imhe Ick attacks fish when their immune systems are supressed. It's often an underlaying problem that causes Ick outbreaks.
I always bump the temp up to 82+ ( depending on what species I'm working with) and do 50% WCs daily for a week. rarely do I get a reoccurence, But it's average life cycle is 1 month... so it cay lay dorement quite awhle before reoccurnence... in severe cases I will add 1tsp per 10gallons dureing that time each day with the water change. And ALWAYS rule out water quality issues first and address if needed.
Salt can kill fish. I wouldn't do more the 1tsp per 10 gallons when adding it to a system, also be wary the beneficial bacteria can be negatively impacted by salinity ( which is why brackish tanks can be hard to maintain)
The Ick parasite is also commonly mistaken for Velvet as well. Which is why anti bacterial and fungal remedies are often used to treat "Ick"
Salt stimulates slime coat production, which to most sounds like a good thing. But imo when you break it down it is further stressing a fish thats already haveing a compromised immune system. Tetra and loaches, and othe scale less fish are extreamly sensitive to salt. Live bearers in particularly mollies do quite well with salt treatments ( likely because mollys and most live bearers can often be found in brackish condition in the wild) I've seen tanks full of clown loaches killed useing salt treatments to try and cure the fish ( one of the most notoriouse fish to aquire Ick outbreaks)
as any "Mediacation" should be a last resort after water quality and toehr factors have been addressed/accounted for.