Help: cooperband fish not eatting sitll...

[Kostas]

So I bought a copperband butterfly fish on Sept 6 and its still not eating. but Its actively picking on all my 150lbs of live rock(but I don’t have anything on them for it to eat),
10days now since I got the fish it still looks healthy – but I’m worried it will get sick soon while it starves to death
It is kept in a 90g, I’ve tested the water all is good.
It’s only other tank mates are a pair of clown fish I’ve had for over a year.
I’ve tried feeding it mysis shrimp, scallops and I bought clam meat this week for it, but still nothing.
I’d appreciate any suggestion