In a soup pot heat oil, whisk in flour to make a thin roux, and cook 3 to 5 minutes, whisking, until raw flour taste has cooked out. Add onions, celery, and green peppers and cook until tender. Stir in tomatoes and bay leaves, reduce heat to very low and simmer 1 hour. A film or crust will form on top of tomatoes; do not stir. Add fish fillets, cover tightly, and cook 5 minutes.
Remove fish to serving plates or a platter, sprinkle with parsley and green onions and adjust seasoning with Creole spice. Serve over rice.
Yield: 4 servings