So if its a matter of territory, when will his YT stop beating the PBT? When he realizes that the PBT has moved in permanently and wont be evicted? Maybe when the PBT gets fed up and starts beating back? Or maybe they just fight till one is left standing.
Shame. I love tangs and wish I had a huge tank so I can add to my collection.
Hey its sad how the tangs can be territorial! But you might be careful and watch your powder blue closely for stress an established yellow can really do some damage. But Normally they calm down. There body shape is different and color too so hopefully you got a healthy enough powder that it will withstand the acclimation process.
Good Luck!!!!
Marine lover
move the rocks around and rearrange the terratory this will reduce the tensions in the tank
yellow tangs are by far the most teratorial in my oppinion a quick re arrange should help