People are also not generally aware that not all fish have significant omega 3's. Corn (and other grains) fed farmed fish only have about the same amount of omega 3's as grain-fed beef. Grass-fed beef, on the other hand, has as much omega 3 as wild fish. See a pattern? Animals fed a natural diet have high levels of omega 3, while grain fed animals are deficient.
Raw walnuts are also a great source of omega 3's.