86 or higher. Yes it stops it from reproduceing and there for ends up killing it. you have to keep the heat up for 10 days or more. I thought I might have ich in my tank so I brought the temp up to 86F for over 10 days and never saw a spot and still no more signs of it. SO if you only see very few spots or none at all i think the heat treatment is the way to go.
BUT there is a rare strain that can live over up to 90F. SO just hope you don't have that kind and the heat is fine.