If fish fillets are large, cut into 5 serving pieces.
Mix sour cream, lemon juice and chili powder.
Dip fish into sour cream mixture; coat with chips.
Place in generously greased 13 x 9 x 2 inch baking dish.
Pour margarine over fish.
Place dish on oven rack that is slightly above middle position of oven.
Cook uncovered in 500° oven until fish flakes easily with fork, 10 to 12 minutes.