I just want to nip this in the butt since it's mentioned as a common theme here. If the fish has Ich, I assure you the tank has Ich and still has it unless the system was run through copper or something else. Ich isn't as horrible as everyone mentions though. A healthy fish should be able to fight it enough so that you do not see the "salt" on their sides. Just because you don't see the salt on the sides doesn't mean it's gone though. It just means the fish is healthy enough to fight it to the point you don't see it.That purple has gotten ich 3 times gone within a week. Ich will pop up eventually, but it’s possible to get rid of it without out having to pull out the fish and treating them.
I'd say about 95% of the tanks in the hobby have Ich. Most are completely unaware of it. It's so easy to spread (coral, inverts, etc) all can bring it over while they are in the protomonts stage.