My cories usually eat the flakes that fall to the bottom of the tank. I also feed them algae wafers. Mine don't seem to like the shrimp pellets much, but will occasionally eat them. Other people say their cories go nuts for shrimp pellets. They seem to like the frozen bloodworms and brine shrimp, too. I think they will like the freeze-dried bloodworms too.
I have never seen my cories go to the top of the tank to eat.