Like beef, chicken, pork, and vegetables seafood lets you know if it's not fresh. If you're not sure, pass on that product and try another source. If you don't know how to filet fish then don't. Ask for filets, picked crab meat, cleaned shrimp, squid, clams, oysters, scallops shucked or on the half shell. These products are ready to be cooked and only require refrigeration between 33-40 degrees until being eaten or cooked within a day or two.
Seafood is delicate and cooks quickly.