Defrosting fish is usually best done in the refrigerator or at room temperature. Only in this way can you ensure that the nutrients in it are preserved to the maximum extent.
You can try to speed up the thawing process by placing the fish in a suitable container filled with cold water in which you have added 1 tbsp. salt or squeeze 1-2 lemons.
Alternatively, you can dip the frozen fish in warm water or thaw it in the microwave, but you risk it coughing and changing your taste.