Combine butter, celery, onion, garlic and green pepper in 13 x 9-inch shallow microwave-safe baking dish. Cover dish loosely with plastic wrap. Microwave on high power for 4 minutes.
Stir vegetables. Season both sides of fillets with salt, black pepper and red pepper. Arrange the fish over the vegetables, with the thickest part of the fillets facing toward the outside of the dish. Pour tomato sauce evenly over the top of the fish. Drizzle with lemon juice. Loosely cover the dish with plastic wrap. Microwave on high power for 6 to 7 minutes or until fish is cooked through. Turn dish around 180 degrees halfway through cooking. Let stand, covered, for 2 minutes. Spoon fillet and sauce over Parsleyed Carrot Rice Pilaf.