My copperband (have had it for 2 years) loves Pacifica Plankton and But he is still skinny.

http://redcoralaquarium.net/online/i...oducts_id=1167

My regals and copperband loves live black worms, pe mysis, ocean plankton and rogers reef food, the regals also eat pellets and flakes.

Try some live mussels. Mine eats live white worms and live mussels and he's really fat. You can buy them fresh at the grocery store and then you brush it under warm running water to remove any parasites and then you open it up and give it to the fish. Mine don't even want to eat the live white worms on the day I put in a mussel. He just love it (and so does my niger trigger!).