CARE AFTER PURCHASE
One of the easiest ways to ruin a good seafood meal is to fail to care for your seafood properly. The rules are simple, but often ignored.
Keep it cold
Use or freeze it quickly
Thaw frozen seafood properly
Fish or shrimp at the market should be in a cooler on crushed ice and should be kept as close to 32 degrees as possible from the time it is purchased until it hits the pan or grill. If possible, take a cooler to the market and transport the fish on ice. Fish fillets should not touch the ice directly, but whole fish can. Allowing fish to reach room temperature, even for just a minute can create off flavors or even complete spoilage. Shellfish should always be purchased live.
For a consistently great result, fish should be consumed the same day they are purchased. Worst case, they should be consumed within 3 days of purchase. I try to avoid freezing fish, but many fish freeze just fine. If you must freeze your fish, do it immediately after purchase. Anyone who freezes seafood regularly should use a vacuum sealer. This is the most effective way to preserve seafood and retain quality. In the absence of a vacuum sealer, cover fish fillets in a freezer bag with a small amount of water. This helps push the air out of the bag. Air is the enemy of frozen fish. Most fish will keep up to 1 year in the freezer, but after 3 months there is usually some deterioration. No method can guarantee a fresh tasting product past 3 months and you risk getting an unpleasant surprise if you leave it frozen longer. Never freeze live shellfish. These should be consumed within a couple days and they must be kept alive until they are cooked.
When fish comes out of the freezer, it is critical to thaw it properly. Never thaw it at room temperature. My favorite method is to leave it sealed in a vacuum bag and submerge it under cold water until it is not quite fully thawed. I don’t want it to be rock hard, but it should still be a little icy. As soon as it starts to become pliable, it is time to start cooking it. Another way to thaw it is in the refrigerator. It should take 6-8 hours to thaw that way, depending on size and how cold the refrigerator is. Never thaw it in the microwave. The more irregular the shape, the more important it is to use proper technique. If a fish is very thick on one end and very thin on the other (a common situation with fish) the thin part will thaw way faster than the thick part. In some cases, the thin side can be spoiling while the thick side can be still frozen.