Susan Lark, M.D. writes the following:

I recently made a disturbing discovery about farm-raised salmon, which is the kind you find at most grocery stores and restaurants. We've all heard that salmon is one of nature's super foods. It's full of wonderful omega-3 fatty acids that keep our hearts, brains, joints, and skin supple and youthful. I eat salmon at least twice a week--my personal favorite is wild-caught sockeye salmon from Alaska.

But almost all of the salmon sold today is farm-raised. Farm-raised salmon contains about the same amount of omega-3 fats as wild-caught salmon. But it also contains extremely high levels of a highly inflammatory compound called arachidonic acid. In fact, the inflammatory effect of the arachidonic acid in farm-raised salmon more than cancels out the anti-inflammatory benefits of the omega-3 fats it contains. That's right: Unless you are eating wild-caught salmon, you are better off not eating salmon at all.

I don't know how reliable this source is, the information was send to me in a e-mail a friend.