TheTodd said:Ideally you observe the fish for a few weeks in a QT and treat if it comes down with anything. There are things other than Ich out there. Treating a fish for something it does not have adds stress. I've heard of people running QT at Hyposalinity levels, but that does not help with something like marine velvet. Copper gets a lot, but it is essentially a poison, so you could be stressing out your new fish for no reason with that.