Heat oil in large saucepan or Dutch oven. Add onion and garlic and cook until onion is tender. Add tomatoes and their juice, basil, 4 cups water and salt and pepper to taste. Bring to boil over high heat. Reduce heat, cover and simmer 30 minutes, stirring occasionally. Add wine, fish fillets and more water, if necessary. Return to boil. Reduce heat, cover and simmer 5 minutes, stirring occasionally. Add shrimp. Cover and simmer 5 minutes, or until shrimp turn pink. Serve in large bowls with French bread, if desired. Makes 4 to 6 servings (C) 1992 The Los Angeles Times Submitted By KAREN MINTZIAS On 01 MAR 95 185949 ~0800