Cook and stir onion, garlic and peppers in oil in 10-inch skillet over medium heat until onion is tender. Reduce heat; stir in remaining ingredients except fish. Cook uncovered over low heat, stirring occasionally, 5 minutes.

Arrange fish in ungreased 12 x 7-inch baking dish. Spoon tomato mixture over fish. Bake uncovered at 355 degrees F until fish flakes easily with fork — 25 to 30 minutes. Sprinkle with snipped fresh cilantro if desired.