To be safe, stick with wild-caught, American sustainable seafood. If your store is selling shrimp cheap, it's probably because it comes from Asia where they don't give a rat's ass about the health of you or your family.
Same with farmed tilapia (sold in every big chain restaurant) and salmon.
Pay more...but be safe. After all, you're eating it for your health, right?
http://health.yahoo.net/experts/dayinhealth/seafood-safety-tainted-imports-are-fishy
