By Robert Bazell, NBC News chief science correspondent
Many studies have shown that eating fish is healthy, but mercury which comes from industrial pollution makes its way into the ocean and into the meat of fish. Adults who eat very large quantities of fish can get mercury poisoning. But the biggest concern is the effect on the brains of fetuses and young children when pregnant or nursing mothers eat fish.
You can read current government guidelines about seafood and mercury here.
Here are two summaries of scientific articles from a group at Harvard that illustrate both sides of this issue: