One to add to this after fighting ich two times, one not successful, the second very successful. Garlic and feed as everyone said, but the one thing I learned on the second try is to have insanely good water quality. The second time, I had pretty good water (but not great), then I did a 10g-20g change 1 to 2x per day for two weeks. (my tank is 420 gallons total). I did constant small water changes and everything was zero across the board. it's about 5-8% per day. It's a pain, but damn it was better. I also used Kick it and something called Metro+