When deep frying fish it takes between 2 and 4 minutes depending on how well done you like your deep fried fish.
For me I like my deep fried fish when it's fried in the deep fryer for 2 minutes which is enough cooking time for me.
To deep fry fish bring the deep fryer and cooking oil to 350 F to 375 F and then place the fish into the deep fryer and check it after 2 minutes.
After 2 minutes the fish should be done enough to eat but you might want to cook it longer depending on how well done you like your fish.
You can use a deep fryer thermometer or a candy thermometer to check the temperature of the cooking oil in the deep fryer.
When deep fried fish is done it becomes flaky and opaque.
You can check the fish to see if it's done by taking a fork at a 45 degree angle and poking the fork into the thickest part of the fish and then pull out some of the fish to see if it's done.
But if the fish has been in the deep fryer for at least 2 minutes at a temperature of 350 F to 375 F of already hot cooking oil then the fish should be fully done and ready to eat.