Copper Banded Butterfly...not visibly eating

[JPotter]

I have a tank with a lot of Aptaisia I now also have a Copper Banded Butterfly. I saw it eat thawed frozen mysis with some enthusiasm at the LFS. It was in a tank with several other CBB and several other assorted fish. It didn't seem to be put off by others crowding about.
It is now in my main tank...has been for 3 days. At first one of the tangs insisted it only be in 1 part of the tank but now it can swim all over and the others don't seem to care...in fact it now dominates some of the others. It spends a lot of time down amongst the rock looking for who knows what..occasionally it picks at the rock surface. It also swims close to the surface looking at the water interface as if something nice might appear. I have never seen it look even vaguely interested in all that yummy aptaisia. In my tank it has no interest in mysis, krill bits, shrimp bits or fish pellets. It appears to be scouting for food, is active and interested in its surroundings..it just never seems enthusiastic about what I offer it.
I expected that if it ate at the LFS it would eat at home.
Is it possible it is picking on pods etc and simply isn't as desperately hungry as when in the LFS tank that had no rock etc.
Even if it turns out to be useless re aptaisia I would like it to thrive.