Cats and humans have vastly different metabolic pathways. As such, there are things that we can do that many animals cannot. One good example is we can eat chocolate, but the thiobromine in it is deadly to dogs because they can't metabolize it. One more common one is that grapes and raisins are deadly to dogs and probably cats as well.
Cats can't catch tuna in the wild, so they probably shouldn't eat it. That is my general rule - if they can't catch it or are not otherwise exposed to it in the wild, they probably shouldn't have it. Can cats have...perch, bass, minnows? Oh yeah no sweat. Tuna? Guess not. Chicken? Sure. Beans? Hell no. Just a general rule of thumb I go by, but what do I know, I have a degree in entomology and my wife is a vet
