Mix cheese and flour in pie plate. Dip fish, 1 fillet at a time, in cheese mixture, turning to evenly coat both sides of each. Heat oil and butter in large nonstick skillet on medium-high heat until butter is melted. Add 3 fish fillets; cook 4 to 5 min. on each side or until fish flakes easily with fork. Remove from skillet; cover to keep warm. Repeat with remaining fish fillets.