When deep frying fish or deep fat frying fish you should bring the cooking oil in the deep fryer up to a temperature of 350 F degrees.
Then put the thawed out fish into the deep fryer once the oil has reached the hot enough temperature and allow the fish to cook in the deep fryer until it's done.
Deep frying fish takes at least 10 minutes depending on how well done you like your fish.
The fish will be fully cooked and ready to eat when the fish flakes easily and the fish becomes golden brown.
For me that means to deep fry fish for 10 minutes and it's done to my liking.