You can't go wrong choosing between wild salmon or yellowfin tuna, but we've got the nutritional scoop on the differences between the two. You can’t go wrong choosing between seasonal fresh fish, like yellowfin tuna and wild salmon. Both contain the same number of calories, but yellowfin tuna (sometimes referred to as “ahi”) is less fatty, offers eight more grams of protein than wild salmon, and is prized for its mild but not fishy flavor. Although wild salmon contains more fat, it also has more heart-healthy omega-3 fatty acids. Yellowfin Tuna.