In a large skillet heat oil over medium high heat. Stir in red onion and cook for 2 minutes. Stir in wine and orange juice and bring to a rapid boil. Reduce heat and simmer for two minutes. carefully add cod fillets and season with salt and pepper. Cover and cook for 2 to 3 minutes. Stir in chopped orange and green olives. Serve hot with parsley-buttered rice.