Do you have any idea how that would turn out if you kept those three tangs together in that tank until they lived out their lives? The OP is asking for long term, a QT isn't long term by any means. 2 months is not an adequet amount of time to see how well fish will get along together. Sure the tangs will be okay for a few months, but what happens when they all reach 5", if they don't have their growth stunted before then, and are starting to get aggressive? The PBT would probably be the victor and control the tank after killing the other two. I am not trying to be snotty or rude, just pointing out things that you may not realize.