Gut It: Remove the fish from the board. Grasping the head in one hand and the body in the other, bend the head sharply downward, breaking the spine. Now bend the body up and twist to separate head from body. Open the belly with your knife, remove the remaining viscera from the body cavity, and rinse well. These instructions are for eating-size cats--say, 4 pounds or less. Anything larger, and you'll have to whack the head off with a cleaver.