Can You Thaw Fish Directly In Water. But there's another factor that can cause this, though it's pretty rare. Depending on the thickness of the pieces of fish it will thaw at room temperature in a couple of hours, in the fridge in three or four hours, in cold water in half an hour (change it a couple of times), under cold running water in five minutes if you keep moving it around, in the microwave at the lowest power also in five minutes.

The basic idea is that you use the difference in temperature between frozen fish and cold water to thaw the fish slowly and safely. This can happen if you submerge the fish directly in water without plastic around it, as we mentioned earlier. How do you defrost cod quickly?