In a deep skillet, cook the butter and flour together over low heat to form a roux. Add the onions, celery, and garlic,and sauté until tender. Add the tomatoes, salt, peppers, and water. Simmer covered for 20 - 30 minutes. Add the fillets and cook until flaky, 15 - 20 minutes.  Serve over rice.       Serves 2.

NOTE: The amount of cayenne here is set for a mildly hot taste. It can be increased up to a full teaspoon for real Cajun flavor!