There are a lot of theories going on with this right now, so there are going to be a lot of changes in the coming years. Some people are saying that Ich is in almost every tank anyway, tangs can get stressed fairly easily, but I think that only comes down to the fact that they are fish that swim an insane amount, and they are being pent up in a small tank where they cannot get a good head of steam anymore. If you have a properly sized tank, they are a joy to have, beautiful fish, and very active, if not, they are going to be stressed and aggressive.
I am guessing you are talking about a hippo tang when you say blue, and not an Atlantic Blue Tang or a Powder Blue, but regardless, all of them can grow to be close to a foot, and the minimum suggested tank is 180 gallons, in order to have the best chance at keeping these fish until their natural life cycle is over, which has shown to be 20-30 years or even more, just make sure you do a proper QT, and have a tank large enough for the fish you get.
You did not mention anything about your personal tank, how large is it and what is in there currently? Those are going to be some of the biggest factors in this decision.