yellow tang aggression

Hi everyone, I currently have a problem with my two tangs. They are both juvenile and from biota! Super great fish although sometimes they don't get along. Now fast forward I purchases a copper band butterfly although I knew the risks I asked to seem them eat and this one was a very sporadic...

I bought a copperband a few months ago, he started with lympho but healed and I conditioned him to eat started with mussels, clams, and worms then progressed to brine shrimp. I added him to my tank eventually with a yellow tang, I began him in an acclimation box for 2 days. The yellow tang began...