Good nutrition will go a long way. Good quality foods, imo i prefer blenxer mush in which i have takin live foods, mussels, clams and a choice of a fresh killed and cut fish, last time i used salmon. I also add in a pack of pe mysis shrimp since i have only heard good things about them. As a last ingredient ill soak, blend and add nori to the mix for that much more of a diverse food.
That concoction complimented with blackworms and most importantly of all a low stress environment. I believe will take care of the problem. I dont believe you have to go fallow and treat ick, ive had ick before and did only what i say here and im very confident it has died off due to my fishes good health. My last few additions never showed any signs of ich nor have i seen any since it disappeared 2 years ago.