In a large pot, cook ground beef with chopped onion, bell pepper, and celery over medium heat until the beef is brown. Season with Cajun seasoning, Old Bay, garlic powder, and paprika. Add chicken broth and bring to a low boil.
Stir in minute rice and bay leaves, then mix in butter. Cover the pot, lower the heat, and simmer for 6-8 minutes. Take out the bay leaves, fluff the rice with a fork, and set it aside.
Dry the catfish fillets with a paper towel. In a bowl, mix Cajun seasoning, paprika, garlic powder, and black pepper. Rub the mixture onto both sides of the fillets, then let them sit for 5 minutes.
Heat a cast-iron skillet over medium-high heat. Add avocado oil and butter. When the butter melts, place the seasoned catfish fillets in the skillet and cook for 5-6 minutes without moving them.
Flip the fillets and cook the other side for 3-4 minutes. Squeeze lemon juice over the top and cover loosely with foil.
In the same skillet, lower the heat to medium and add chopped onion, bell pepper, celery, and mushrooms. Sauté for 3-4 minutes, then add minced garlic and cook for 30 seconds. Add crawfish and shrimp, season, and cook until the shrimp turn pink.
Pour in heavy cream, reduce the heat, and mix in Parmesan cheese. Cook until the sauce thickens, about 4-5 minutes. Adjust the seasoning if needed.
Spoon dirty rice onto a plate, add a blackened catfish fillet, and pour the Opelousas sauce over the top. Garnish with chopped green onions and a sprinkle of paprika. Serve immediately.