Almost all online dealers, wholesalers, and many dealers & hobbiests, use copper on almost all new fish. I've used copper and a de-wormer in QT for years with great success. Copper shouldn't be used on a few very copper-sensetive fish (like Flame Angels) or any invert; but at well monitored levels I consider it perfectly safe. I really don't understand the big deal; copper needs to be monitored, but one drop of copper treated water isn't going to kill anything. There is even some copper in Instant Ocean. I also think the idea that silicone sealant holds and releases copper to be silly.