it turns out you CAN eat too much fish! i just read this article: http://www.aces.edu/dept/extcomm/newspaper/nov20a03.html
and it talks about the fact that eating too much saltwater fish like tuna exposes you to alot of mercury, which is toxic to humans when present in high amounts, and which accumulates in the body over time.
the article says (based on what doctors say) that you should eat two meals of tuna per week maximum to avoid the possible health concerns regarding mercury.
so there ya have it!