Thaw fish, if frozen. Rinse fish and pat dry with paper towels; set aside.
Line a large baking sheet with foil. Spray foil with nonstick spray coating. Arrange potato sticks in a single layer over half of the baking sheet. Brush potatoes with oil or the 2 teaspoons melted margarine. Sprinkle with garlic salt. Bake in a 450 degree F oven for 10 minutes.
Meanwhile, stir together stuffing mix and the 2 tablespoons melted margarine. Place fish on baking sheet next to potatoes. Sprinkle stuffing mix over fish. Return pan to oven and bake 9 to 12 minutes more or until fish flakes easily when tested with a fork and potatoes are tender. Makes 4 servings.