Frozen fish fish want to thaw it for a pet?

ok about 4 or 5 years ago i cot a huge b and i wanted to mount it but i never got around to it.so thinking i could mount it i put wrapped it in a trash bag thingy and put it in a cooler it was in there for about and hour then i put it in a freezer and now i wanna thaw it out and put it in a fish tank is there a good prosses of which i can thaw it out like should i put it in the fridge and then put it in the water or just let it thaw out in the water plz helo it is a really cool fish. its about 18 inches