I just got my baby blue tang 2 days ago and I noticed he’s scratching against the PVC. It’s in my QT. NO WHITE SPOTS YET. It’s swimming and eating just fine but should I treat it? Should I treat it with Prazi or copper?
Kind of a judgement call. Could be flukes, could be ich. Some people go ahead and treat for everything, and some wait until they are sure what needs to be treated.
Blue tangs have a thin slime coat. If they are scratching today and it's ich, they will likely have spots in a day or 2. You can do a freshwater bath in a black bowl to knock flukes off, and if you see them, treat with prazi, but there are other symptoms also.
Check out the fish disease section, there are some combinations you can dose at the same time, and some you should avoid. There is a lot of useful information in it.
I pretty much treat for everything in my QT, unless I know it's a sensitive fish that will struggle. Then I'll monitor. My blue tang was treated for everything and was fine. Ammonia build up is the biggest worry in QT IMO. That is how I've lost the most fish, and I don't trust those little seachem window things anymore. Either I can't read it properly, or they don't work.
Even though I did all that QT, and went fallow in my tank, ich still managed to get in somehow. So I either failed at the QT, or the ich came in on a snail or something. Good luck, I'd give quite a bit if I could get rid of it in my tank, but I can't catch my fish.