Melt butter in a medium skillet over medium heat. Add diced onions and cook for 3-4 minutes until golden. Add garlic and parsley and sauté until fragrant, 2 mins.
Stir in crawfish tails cooking on low heat for 5 minutes. Add heavy whipping cream and stir until the sauce is warm and thickens. Add Cajun seasoning, Worcestershire sauce and green onion stirring occasionally. If sauce isn’t thick enough add 1 ½ tbsp of flour to sauce and stir well to combine. Let sauce simmer while you cook fish.
Melt butter in a large skillet over medium heat. Sprinkle fish evenly on both sides with paprika, Cajun seasoning, salt and pepper. Add fillets to pan; cook 4-5 minutes flip and squeeze 2 tbsp lemon juice and finish cooking 4-5 minutes. Fish is cooked when it becomes flaky. Remove fish from skillet; keep warm. Place fish on plate then top with the creamy crawfish sauce. Enjoy!