Wild: The word evokes lone fishermen in small boats. In reality, wild fish are often caught by big ships dragging large nets, lines, or dredges, which deplete fish populations and pick up unintended "by-catch," says Sheila Bowman, Seafood Watch outreach manager at the Monterey Bay Aquarium, in Monterey, California. In general, opt for U.S. farmed fish over wild.
Farmed: Many fish―like rainbow trout, striped bass, and shellfish―thrive in farms, where they are raised in underwater pens. But a few types―like Atlantic salmon and imported shrimp―are often raised with troubling practices. Because these varieties are carnivorous, they need to be fed great quantities of wild-caught fish, and that contributes to overfishing. In addition, they're crammed into small pens in huge numbers, increasing their risk for disease. Fisheries try to fight this risk by feeding the fish large doses of antibiotics, which linger in our water. At the market, go for wild salmon and American farmed shrimp.
Country of Origin: Federal law requires that fresh and frozen fish in stores be labeled with the place it was caught or processed. As a rule, "Made in the USA" is a good sign. "Our fisheries aren't perfect," says Tim Fitzgerald of Environmental Defense. "But we do have more safeguards in place than Asia or Latin America, where most of our other fish comes from."