Melt butter in a large skillet over medium heat.

Add onion, celery, bell pepper, and garlic to the skillet.

Stir constantly for 5 minutes, until softened.

Stir in crawfish, salt, black pepper, cajun seasoning, thyme, onion powder, white pepper, and hot sauce.

Cook for 5 minutes, stirring occasionally.

Stir in flour and cook, stirring constantly, for 2 minutes to create a roux.

Gradually stir in fish or chicken stock.

Cook over low heat for 20 minutes, stirring occasionally, until the sauce has thickened.

Stir in green onion and parsley.

Cook for 3 minutes.

Serve hot over cooked rice.