They studied 677 people living rural coastal areas of Ecuador. Blood pressure decreased progressively with up to five servings of fish per week.  Consuming six or more servings had no further effect on blood pressure.  The U.S.A.  Department of Agriculture recommends one or two servings of fish per week. This study showed that increasing fish intake above these levels might have added cardiovascular benefits. The study did not examine the effects of fish oil supplements. Other studies found that fish oil is good for the heart and circulation.