shrimps/crabs/scallops are awesome because they are high protein, no carbs, and very little fat. If on any type of keto diet, then these will allow you to eat some natural PB with each meal for some good fats!!
I was looking at my bag of frozen shrimp (the little kind used for salads), and they had Zero fat, Zero carbs and 17g of protein per serving (3/4 cup I think). Too bad it costs a bitch.