At 32° your fish will not freeze and stay fresh for up to 14 days.
At 40° your fresh fish will only stay fresh for 7 days, and as you may know, most residential refrigerators are set to about 50°. A solution is to place your fish in a bowl of ice in your refrigerator as soon as you get it home, until you cook it. Ocean’s Table recommends that you plan to eat your fresh fish within 10 days from the time you get it home.
Handle and prepare seafood properly.
All foods, including seafood, must be handled and prepared in a clean area to avoid cross-contamination. Always remember to keep your hands, preparation area and utensils clean. Never let raw seafood come in contact with already cooked or ready-to-eat foods (e.g. salads, fruit, smoked fish). If you are storing fresh fish in your refrigerator, make sure that the juices from raw seafood do not drip onto food that has already been cooked or food that will not be cooked.
Marinades are great for seafood but should not be saved and used as a sauce unless the marinade has been cooked to a temperature of at least 165°F to eliminate microorganisms from the raw fish. Always marinate in the refrigerator in a glass or plastic container.
Never serve cooked seafood on a plate that held the raw product without proper cleaning. Store leftovers, properly wrapped, in the refrigerator within 2 hours. Bacteria will grow rapidly in the temperature “Danger Zone” of 40-140°F so keep hot food above 140°F and cold food below 40°F.
Source: http://www.seafoodhealthfacts.org/seafood-safety/general-information-patients-and-consumers/seafood-handling-and-storage