If the fish had very low levels (as the ones in the safe list) and you had no other mercury source like fillings, and you get more than enough minerals (minerals are crucial in chelating mercury), and are healthy otherwise for the most part...then, I am guessing the nutrient value would surpass the damage done by the mercury.  But, I am not certain.  I would actually have to get Hal Huggins' opinion to feel good about that statement.  I'll email it to him, but he's busy and sometimes takes a long time to answer.   

Spirit doesn't like forum owners to post in debate rooms (because they can get so bad in there), so that is why I didn't post in quackary debate.