no once the ich is gone it cannot reapear out of thin air no matter how stressed the fish is. unless you re indroduce ich into the tank by not qt'ing your fish
Yep. If it comes back, you either didn't quarantine all of your fish, or you didn't quarantine/treat for long enough, or you introduced something new carrying it.
Thanks, guys. I'm thinking about getting this blue hippo from someone, and of course I'm going to QT it. I've asked the guy if he's treated it for ich before, but would it hurt to qt him again with copper?