Nature's Recipe, a brand of cat food made by Heinz Pet Products, claims to make "a variety of complete and balanced diets... in flavors and forms cats naturally crave, including Chicken, Turkey, Lamb, Tuna, and Rabbit & Rice formulas."

As far as I know, considering the little guy has never seen the ocean and hates water with a passion, tuna is not one of the foods my cat would have access to if he was in his natural environment. In fact, being a house cat weighing roughly eight pounds, the idea that he could not only catch, but kill and devour an animal weighing more than twice what he does* is preposterous; adding to that the fact that he'd have to swim a couple hundred yards offshore before doing so is just icing on the cake.

I would believe that a cat might naturally crave a chicken or a rabbit (where the pot of boiling water needed to cook the rice comes from is another issue altogether). A lamb is pushing it--we run into that whole "cats are dinky" issue again. Saying that a cat naturally craves tuna is just absurd.

It has been brought to my attention by both dem bones and stewacide that tuna can grow to be much more than twenty pounds in weight. It should be noted that the tuna mentioned in this node is the albacore tuna, which is a smaller fish, weighing between five and twenty five pounds. The friggin' huge tuna are the yellowfins, which can weigh more than 300 pounds, and therefore are much more than twice the size of my cat.

Information on the size of albacore tuna from:

Information on the size of yellowfin tuna from: