Always buy the freshest fish you can. The eyes should be clear, and there shouldn't be any fishy odor. In storing seafood, the operative word is 'cold.' Store fresh fish in the coldest part of the refrigerator and plan on using it within two days. Mollusks such as oysters, clams, and mussels, should be refrigerated in containers. Cover them with damp cloths, rather than lids. These should be alive when you cook them. If you see one with its shell open, give it a tap. Live ones will close back up. If it doesn't close, throw it away. Live crabs and lobsters should be cooked the same day you buy them. Once cooked, they should be eaten within two days. For longer storage, fish and seafood can be frozen and stored at zero degrees for up to six months, but the longer they're stored, the more flavor they lose.