Hypo should not stress fish.
You should not catch heat, as it is your tank and you can do whatever you want., IMO.
You need to understand that if one fish has Ich, it IS in your system now and will not magically go away. Best case scenario is the fish left in the tank stay healthy enough to fight it and keep it at bay and the QT Tang gets healthy and can somehow fight it off when it is exposed again upon re-entry. Unless it is really bad off, I would almost not QT it.
Any new additions run the risk of getting Ich moving forward too. I would still QT, as they could have something else worse, like Velvet.
You should not catch heat, as it is your tank and you can do whatever you want., IMO.
You need to understand that if one fish has Ich, it IS in your system now and will not magically go away. Best case scenario is the fish left in the tank stay healthy enough to fight it and keep it at bay and the QT Tang gets healthy and can somehow fight it off when it is exposed again upon re-entry. Unless it is really bad off, I would almost not QT it.
Any new additions run the risk of getting Ich moving forward too. I would still QT, as they could have something else worse, like Velvet.

