Anthias, Picky eater

[foxface]

Hi everyone,
I just got a bicolor anthias, big one too, 5"! Anyways, he's a really picky eater. He only wants to eat frozen Brine or Mysis shrimp and since that's pretty much the fish equivalent of our junk food, it gets me worried. I've tried frozen plankton (all Hikari Brand) and he spits it out?!? I even tried to trick him by mixing the mysis and the plankton and he still spits them out and eats the mysis instead.
I've tried flake, pellet, frozen formula 1 and formula 2 (which I didn't think he'd eat but it was worth a try) and he won't touch them. The brine and mysis shrimp, he gobbles those up with gusto and it's like there never enough of them! I know he should eat several times a day and since he's in a 10 gallon QT, it's really keeping me busy with the scooping out of uneaten food although I've stopped experimenting with him and the small flame angel that's in there with him eats almost anything so there wasn't that much to take out.
What should I do, is there anyone out there with this problem? Is it OK for him to eat just the shrimp. I almost forgot, I also tried a piece of raw table shrimp and he didn't like that either!
If he does end up on a diet of Mysis, is a whole cube too much for him since he's 5", in the QT it's gone in no time at all and the little angel gets hardly any of it.
Louise