Photo by Lew Robertson/StockFood Thanks to reasonably tight regulations, seafood from US waters is more likely to be responsibly caught. And by buying American, you take us all a step away from a screwy situation—more than 85% of the fish we currently eat is imported, while the US exports a full one-third of its fish.   2. Go low on the food chain. Photo by Owen Franken/Corbis Images The creatures at the bottom generally are more plentiful and grow faster. They also happen to contain fewer contaminants. Healthy fish that are low on the food chain include anchovies, sardines, and herring. There are also some large fish that eat low on the food chain and contain fewer contaminants: wild pink salmon and sockeye salmon. MORE: 3 Tasty Ways To Give Sardines A Try   3. Don’t forget the guys in shells. Photo by The Picture Pantry/Alamy Not only are clams, mussels, and oysters high in nutrients, but they’re also beneficial for the surrounding environment. These filter feeders, as they’re called, don’t need to be fed anything to thrive—they feed themselves by cleaning the waters around them. A single mussel or oyster can filter up to 50 gallons of water per day. That goes a long way toward making our oceans more friendly for the other seafood that we’re in peril of losing. Incidentally, these shellfish are also low in calories and high in omega-3s (mussels have as much as tuna, and far less mercury). (Give this delicious steamed mussels recipe a try.) MORE: How To Cook Fish So It Doesn’t Smell