Tilapia, a farmed fish, is commonly sold as frozen, deboned, skinned fillets. With firm, white flesh and a mild flavor, tilapia pairs well with many vegetables, spices and sauces. The fillets can be cooked directly from a frozen state or defrosted beforehand. Frozen fillets do not absorb the flavor of marinades and rubs as well as thawed fillets. Fresh tilapia can be filleted and then frozen for future use.
Defrosting Frozen Fillets
To safely defrost your tilapia fillets, place them in a bowl, cover it and leave the bowl overnight in the fridge. If you don’t have time to defrost them in this manner, place the fillets in a plastic bag and submerge the bag in a bowl of cold water. Do not use warm water as this creates an environment friendly to bacteria. Use a plastic bag; otherwise, the flesh will absorb the water as it defrosts, affecting the taste of the fish. You can also defrost fillets using a microwave’s defrost setting.
Cooking Thawed Fillets
You can cook the fillets in a hot frying pan; the hotter the pan, the crispier the fish. Alternatively, bake the tilapia in the oven. Because of their firm flesh, tilapia fillets can also be grilled. Thawed fillets can be marinated or seasoned with a dry rub prior to cooking. Put the fillets in a sealed plastic bag along with a marinade made using wet and dry ingredients. Let the fillets marinate for 20 minutes to an hour. A marinade penetrates the flesh of tilapia faster than a dry rub. When putting dry rubs on your fillets, gently pat on the spice mixture. Do not rub it in, as the flesh is delicate and tears easily.
Cooking Frozen Fillets
Fillets can be cooked from a frozen state, which is useful if you don’t have time to defrost them. Frozen fillets cannot be marinated prior to cooking, but adding a flavorful sauce during or after cooking is possible. You can poach, steam, bake, broil or grill fillets from frozen. To cook fillets from frozen, rinse them under running water to remove any frost, and then pat them dry. After brushing on the marinade — even just a thin layer of olive oil can work — cook the fillets until they’re done. The fillets are done when the flesh is firm but not rock hard and when it flakes easily with a fork.
Freezing Fresh Fillets
To freeze fresh fillets, pat-dry the tilapia and wrap it in plastic wrap or place it in a heavy-duty freezer bag. If you’re using plastic wrap, wrap the fillets in a double layer, either individually or in pairs. You cannot re-freeze defrosted fish, so avoid having large packets of fillets as they may spoil when you cannot finish all of them after defrosting. With both plastic wrap and bags, make sure the plastic touches the fillets directly with no air bubbles. Oxygen bubbles can lead to oxidation, and an airtight seal also minimizes the chance of freezer burn. The colder the freezer temperature, the larger the package of fish, and the more tightly sealed it is, the longer frozen tilapia can be stored for. Home frozen fish can typically be frozen for at least two to three months, and longer if well-packaged and kept in a very cold freezer.
References and ResourcesFood and Drug Administration: Fresh and Frozen Seafood -- Selecting and Serving it Safely
The Kitchn: Skip the Thawing -- Cook Frozen Fish Straight From the Freezer
Bon Appetit: How to Cook Fish Fillets Perfectly Crispy Without a Recipe
University of Alaska Fairbanks: Home Freezing of Fish
The Joy of Cooking; Irma S. Rombauer