Copperband eating, but getting thinner.

[Douglas]

I've had my copperband for 3-4 months, and i've got it eating brine......but thats all. It's getting thinner, and thinner. What can i do to get it to eat more, or something different, to try to fatten it up a bit. I've tried mysis, Pacifica plankton, Krill, blood worms. But it'll only eat brine. Doesn't touch aiptasia either. Any Ideas?