Storing Fish: What You Need to Know
One of the questions I'm asked most often at our fish market is "How should I store my fish?" The simplest answer is to keep it in the refrigerator until you're ready to cook it later that day. Most of us though don't have the luxury of daily shopping. When you need to shop ahead, here are some tips to keep your seafood in top-notch shape at home.
TO STORE FISH OVERNIGHT OR FOR MULTIPLE DAYS:
The first thing you'll want to do is remove its packaging. Butcher paper or deli paper can adhere to fish and become tough to remove. I recommend storing filleted fish in a sealable plastic bag. Squeeze as much air as possible from the bag before sealing. Take a large colander and place some ice in the bottom. Flaked ice is ideal here if you have it on hand. Put your fish in the colander and cover with more ice. Nestle the colander in a bowl to catch the ice melt. Store the whole contraption in the fridge, draining and re-icing your fish once a day until you are ready to cook it.
If your freezer doesn't have a flaked ice option, you can store your fish in a slurry of ice cubes and water. Immerse the sealed bag of fish in the ice cubes and water and store in the fridge. Drain some of the water and add more ice once a day until you're ready to cook your fish. These two techniques can also be used to store whole fish. I don't advise storing fish directly in/on ice or in ice water without the protection of a plastic bag.
HOW LONG CAN DIFFERENT TYPES OF FISHES BE STORED?
Not all fishes are created equal when it comes to how long they will store well. Using the above storage methods and assuming the fish you're buying is very fresh, these are good rules of thumb for different types:
Lean white-fleshed fishes (bass, snapper, hake, pollock, haddock, monkfish, flounder, etc.), pelagic fishes (tuna, swordfish, etc.), and members of the salmonid family (trout, char, and salmon) should keep well for 3 to 5 days. Oily fishes (mackerel, bluefish, sardines, mahi mahi) are best consumed within 3 days of purchase. Skate is the one fish I recommend you cook the day you buy it. Skate, sharks, and rays have high concentrations of urea in their bodies that convert to ammonia over time. Eventually this will cause an unpleasant odor and flavor to develop in these fishes. Better to avoid this possibility altogether.
CAN FISH BOUGHT FRESH BE FROZEN?
Generally I try to avoid freezing fish, but it's better to freeze it than have it go to waste. If you need to freeze, there are a few things you can do to optimize the process:
When freezing, your goal is to make sure the freezing process happens as quickly as possible. If you happen to have a blast freezer at home, use it! Given that most of us don't, you can speed up the process in a regular home freezer. Line a cookie sheet that will fit in your freezer with plastic wrap. Arrange your individual fish fillets in a single layer on the wrap, making sure they do not touch. Cover the fish on the tray with another piece of plastic wrap and freeze. After about 2 hours, the fish fillets should be frozen enough that they are firm and easy to handle. Once this is done, transfer the fish into a sealable freezer bag (squeezing out as much air as you can before sealing). Shrimp and squid will also freeze well using this technique. You should consume seafood frozen this way within 30 days.
Fish that has been frozen at home will always behave a bit differently than fresh fish. It can become a little stronger in flavor and lose some of its water content. As such, you'll have more success with wet cooking methods like braising or poaching than you will with dry methods like roasting or grilling.
IS BUYING FROZEN FISH A GOOD OPTION?
Commercially frozen fish is generally of very high quality and can be an excellent value. It also has a much longer shelf life than fish frozen at home. It will be labeled with a "best by" date. Look for fish fillets that have been vacuum-packed and blast-frozen. A lot of frozen seafood is treated with polyphosphates to help it retain water. Polyphosphates are not generally considered to be harmful to human health when consumed in small quantities. They can, however, affect the quality of frozen seafood. Look for untreated frozen seafood if it is available.
When you want to use frozen fish, you should plan a little ahead: The best way to defrost any frozen seafood is slowly in the refrigerator. This will take 12 to 18 hours (overnight) depending on the size of the piece of fish.