【How-to】How much potassium in salmon

You want to avoid high-potassium surf such as halibut, tuna, cod, and snapper. 3-oz servings can contain as much as 480 mg of potassium. On the low end, the same amount of canned tuna has only 200 mg. Salmon, haddock, swordfish, and perch run about 300 mg per 3-oz serving.