Thanks for the replies, due to the fish variety in my tank, 2 groupers, a dwarf lion, two tangs, 4 different gobies, a clarkii, and a molly I have to feed a varied diet to the tank.
I use, Krill, silversides, brine shrimp (on occassion), flake, pellet, formula 1&2, seaweed, and the occassional clam or shrimp.
I rotate all of this. So the groupers get their meat. Yesterday was the first time I saw the grouper eat the flake though which is why I asked if anyone else had ever seen it done. I never see my other grouper eat but he is twice the size of the other one. So he must be eating sometime.