The Safe Food Handbook has a chapter dedicated for Fish and Shellfish. Why? Because I believe seafood, and especially farmed seafood, is becoming increasingly dangerous to eat.
1. Raw is risky
2. Wild is usually safer than farmed
3. Small is usually safer than large
4. Domestic is usually safer than imported
5. Fish fat and fatty fish are best avoided
6. Dark parts of shellfish are more dangerous than light parts
7. Diversification is a good idea.