They are really high in omega 3 fatty acids, those are the really good fats. They are also very high in protein and high quality protein and relatively low in saturated fat.
About 10 years ago studies found farm raised salmon contained more contaminants than the wild due to run off from the fish pens as well as chemical pollutants in the feed. But, that is not so much the case now.
In the past decade that gap has been closed largely because of improvements in farming techniques as well as improvements in the feed salmon are given.
Water pollution can affect all salmon, but you can help protect yourself by the way you cook. Start by removing the skin, and removing as much fat as you can. And then grilling or broiling to let that fat run off because those pollutants are stored in the fat of the fish.
Whether you choose farm or wild salmon health experts say you are doing your heart a favor.