01 - In a shallow dish, whisk together buttermilk and hot sauce. Add catfish fillets, ensuring they're fully coated. Cover and marinate in the refrigerator for at least 15 minutes (up to 1 hour for deeper flavor).
02 - In a large plate or shallow bowl, combine cornmeal, flour, Cajun seasoning, garlic powder, paprika, salt, and black pepper. Mix thoroughly to distribute spices evenly.
03 - Heat 1 inch of vegetable oil in a deep skillet or Dutch oven to 350°F. Maintain temperature throughout frying for optimal crispiness.
04 - Remove catfish from marinade, letting excess drip off. Dredge fillets in the cornmeal mixture, pressing gently to adhere coating on all sides.
05 - Fry fillets in batches, 3–4 minutes per side, until golden brown and crispy. Transfer to a paper towel-lined plate to drain excess oil.
06 - Combine mayonnaise, dill pickles, capers, lemon juice, Dijon mustard, and parsley in a bowl. Mix well and season with salt and pepper to taste. Refrigerate until serving.
07 - Serve fried catfish hot with tartar sauce on the side. Accompany with coleslaw, hush puppies, or fries for a complete Southern meal.