The study found that eating baked or broiled fish at least once a week gave people a 4.3 percent increase in brain volume in areas associated with memory, and a 14 percent increase of brain volume in areas associated with cognition. Hhmmm... And I thought by buddys big heads were just their ego's kicking in when they claimed to actually caught a fish!!
Actually, those studies just showed changes in the volume of certain areas of the brain are correlated with people who report eating baked or broiled fish... they did not prove that eating baked/broiled fish CAUSED any changes in the brain, nor did they show that those changes in brain volume were associated with better memory, etc.
Interesting, but not really a smoking gun that links fish-eating with anything all that great....