All the health professionals say that eating Omega 3 fatty acids are VERY important for your heart & overall health.
One of the most excellent sources of Omega 3's in food is fish, primarily tuna & salmon. But there is also controversy about how much tuna is safe, because tuna typically contains certain trace amounts of Mercury, an element that is pretty darn nasty to ingest into your body.
I don't know exactly how much mercury is in tuna & salmon, or if the benefits of getting the Omega 3's outweigh the negatives of ingesting mercury. I don't even know how much mercury is a "safe" amount.
So it would seem more research is needed on this topic.
In the meantime, or if you're worried, consider taking a vitamin supplement of "fish oil" which contains Omega 3's, instead of eating fish.
Omega 3 is an extremely important nutrient for your body; so one way or another, it would probably benefit you to get it!
If anyone knows anything more specific about this topic, please feel free to comment.