How do you properly defrost frozen fish?

There are two safe ways to defrost, one more rapid than the other.

First method is to defrost in the refrigerator. This keeps temperature below 40 degrees F, in the safe zone. This will, also, take a while.

Second method is to defrost in the sink under cold running water. The water doesn't have to run rapidly, but it should change regularly. This will defrost the fish more rapidly than in the air (water is a better conductor of heat than air) and will keep the fish in the danger zone for the shortest period of time. If you are not going to cook it immediately, then return to the refrigerator.

If you are deep frying, there are some techniques that will allow you to go direct from frozen to fried, but that is generally done in a professional kitchen where they have powerful fryers that can take the temperature hit and come back strong.

From the FDA website:

Thaw frozen seafood gradually by placing it in the refrigerator overnight. If you have to thaw seafood quickly, either seal it in a plastic bag and immerse it in cold water or — if the food will be cooked immediately thereafter — microwave it on the “defrost” setting and stop the defrost cycle while the fish is still icy but pliable.

Defrosting quick frozen fish in fridge is the most recognized way but far from the best. Quick-frozen fish (or any food) is frozen in a short time which means that the ice crystals will be very small which is most important to preserve the quality of fish.

The risk to miss this quality happens when you start to defrost the fish. Doing it very slowly as by keeping the fish in fridge overnight means that this slow defrosting process creates big ice crystals in the fish meat; loss of valuable protein and liquid and fish becomes dryer and less tasty.

Therefore the main matter in defrosting is very simple. As it is beneficial to freeze quickly, the same goes with defrosting. Therefore for best result: Defrost in water 18 - 20 C in sink or in a big ball. Defrosting will take less the one hour and it is not necessary to use running water; the cold water nearest to fish will move by itself.

I have a little to share based on my experience as a restaurant owner, there are 5 ways to thaw the fish properly and safely.

1. Place it in the refrigerator, this slows down the icy crystals inside the fish.
2. Put it in a running water, cold preferably, to maintain the toughness of the meat.
3. Cut the fish to desired size before cooking for a couple of minutes.
4. Thaw the fish by salting more faster than the rest of the methods.
5. Place it in a sealed bag then thaw it in a bowl of water.