Is Tuna Good for cats? Or dangerous? And why?

9 Lives Essentials makes a tuna just for cats that you can buy at the supermarket.
There are also several brands of tuna cat food and tuna cat treats containing real tuna on Amazon. There are so many options now for giving cats safe pet grade tuna that there's no excuse to buy human grade tuna for your cats. The only human food I give my cat is a little piece of chicken or turkey if I happen to be having some for dinner.