I believe tuna and other deep sea/cold water fish have chicken beat
Some sites do say that, but you’d have to eat fish.
https://www.mindbodygreen.com/articles/what-meat-has-the-most-protein
I love tuna steaks. When Fry’s (Kroger) has them on sale, I ask the meat department guy to get me a couple from the freezer so I can thaw them right before I cook them.