Preheat the oven to 375°F.
Rub the redfish with the oil and place in a large baking pan. Cut several slits in the top half of the fish and bake for 40 to 45 minutes. In the meantime make the tomato sauce. In a large saucepan combine the tomatoes, bell peppers, onion, garlic, and water and bring to a boil. Simmer, covered, for 30 minutes. Pour the sauce over the redfish and bake 5 minutes.
Makes 4 to 6 servings