Skip the oil or pill supplement and just go right for the real deal when it comes to iron-rich fish,” Martindale says. Seafood-based iron is a very healthy source of iron, which is especially high in oysters, clams and mussels, she adds. “But some of the top fish based sources of iron are sockeye salmon (which has approximately 0.4 milligrams of iron in 3 oz.), baked halibut and light tuna canned in water.”