Fish provides protein and good-for-you fats, making it a great base for flavorful meals. When buying from your fishmonger, look for fillets that are dense and without gaps between the layers. And if you are buying fresh fish wrapped in plastic, make sure that it doesn't have a lot of liquid in it.
Avoid frozen seafood if its package is open, torn, or crushed on the edges. Also make sure that the fish isn't positioned above the “frost line” or top of the freezer case, or that have signs of frost or ice crystals, which may mean the fish has been stored a long time.