The Australian Fisheries Research and Development Corporation published
last year their analyses of fats some farmed Australian fish.  I have
placed a summary of their tables at:

http://www.evfit.com/fish2.htm

It shows that there can be over 100 times as much of some Omega 3s in
farmed as in wild fish.  These data are not misprints.  It is my guess
that these farmed fish had some fish meal in their diets rather than just
the cheapest grains around.

Keith