Thoroughly wash the fish fillets under cold running water. Check to ensure that all bones have been removed. Divide the fish into 8 equal pieces ? 2 per serving. Carefully dry with paper towels and dredge each piece in seasoned flour, shaking off the excess. Heat oil to 375 degrees F to 400 degrees F. At the same time heat up 1 inch of oil in a heavy-bottom frying pan to the same temperature. While the fat is slowly getting up to temperature, drain the potatoes, getting as much moisture from them as possible with paper towels. Dip each piece of fish into the batter mixture. Allow excess batter to drip back into the bowl and gently immerse the fillet in the hot oil. Do not cook more than 2 or 3 pieces of fish at a time. The inside of the fish will be cooked when the outside batter is a mid to light brown. Turn the oven to low so that you can keep the cooked pieces of fish warm while the others are cooking. Take 2 handsful of potatoes and carefully release them into the deep-fryer. When golden brown, remove with a slotted spoon so that you can shake off the excess oil, and turn onto paper towels.