How bad is copper?

[jon.smolders]

There's a store in town that's only 2 minutes from my house that has some cool SW fish and inverts, but I noticed on some of their tanks they wrote "copper Apr 20"... how bad would it be to buy a fish or two from them if they've treated their tanks with copper? I know copper can get into the silicone and then leach into the tank later on, so would it still be a concern even if they've done water changes? Their tanks aren't always great looking, but most of their fish look healthy. I have a reef tank with some mushrooms, zoas and LPS... if I net the fish after acclimation would this be enough to prevent copper from getting into my tank? Just curious...