I don't think it takes a month Laura. I'm pretty sure the parasite is dead within days if it doesn't reattach. I dunno I'd have to check on that one. Anyway, that's what I do, remove who's infected and their species mates only, and watch the rest in the meantime. After a few weeks and no one else becomes infected, the cured and QT'd ich fish go back in. Has worked that way every time without a hitch, no reinfection. Maybe it's the fisherman in me and I just like to wrangle them up, or it's just that whenever I see a sickly fish in my display tank, my first instinct is to get that nasty sucker out.