we do the same. I go to the seafood counter and buy several medium size shrimp. Take it home, clean it up, chop into about 3's. Freeze. 1-2 times a week I thaw a piece and usually "Chip"
will be at the top of the tank begging. He lays outward as if to sun himself. We just place a piece right in the middle and he grabs it. His stomach comes out

and he usually takes the rest of the day to eat it. He is fun to have in the tank, very busy. (not reef safe though) make sure your rock is very stable.