Sprinkle catfish with Cajun seasoning. Place large skillet over medium-high heat. Add butter and olive oil. When butter is melted and hot, add catfish. Cook 4 minutes, turn and cook another 4 minutes. Remove from skillet, and set aside. Add onion, celery, bell peppers and mushrooms to skillet; cook 4 minutes. Add garlic; cook 2 more minutes. Add heavy cream, stirring to combine. Cook 4 minutes or until cream mixture has reduced by half. Season with hot sauce, salt and pepper. Split biscuits, and place on serving plate. Cut fillets in half; place one half on each split biscuit, and spoon sauce over each.