i would do 25% or more water changes daily or bi daily until the ammonia spike resolves... then hit the tank with prazi pro... then get him off live... starveing a sick fish equals dead fish. night crawlers would be good, my guy went crazy for live black worms. if he'll take them right away great... but i wouldn't try and convert him until the health issues are resolved.... clean water, and prazi to deworm, gill flukes also show these symptoms and will kill if left untreated. like caught a bacterial infection from the feeders, and ammonia spike compromised his immune system. salt will only stress himout more imo, and the increase in slime coat production because of this will use up what reserves he does have.