First, make the roux. Heat and melt butter and oil in a large pot and add your flour. Wisk in until incorporated and switch to a wooden spoon. Stir continuously for a good 20-25 minutes or until your roux is dark, but not burned.
Add your chopped onion, celery and peppers and stir well into your roux. Cook until the vegetables are cooked down and soft, for about 15 minutes.
Add in your spices and bay leaves and stir well.
Next, add in your cubed fish and stock and stir to combine. Bring it to a boil and then decrease to medium/low. Cover and simmer for 40 minutes to an hour.
Finish by stirring in 2 teaspoons of filé and serve over rice or with crackers. Enjoy!
You can use all oil if you prefer or all stock.