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.