01 - Whisk together buttermilk and hot sauce in a shallow bowl. Add catfish fillets, turning to coat thoroughly. Cover and refrigerate for at least 15 minutes, up to 1 hour, to allow flavors to penetrate.
02 - Combine cornmeal, flour, Cajun seasoning, paprika, garlic powder, salt, and black pepper in another shallow dish. Mix well to distribute spices evenly throughout the coating mixture.
03 - Remove catfish from marinade, allowing excess liquid to drip off. Press each fillet firmly into the cornmeal mixture, turning to ensure complete coverage on all sides. Shake off any loose coating.
04 - Pour vegetable oil into a large skillet or deep fryer to approximately 1 inch depth. Heat oil to 350°F, maintaining temperature throughout cooking for optimal crispiness.
05 - Fry catfish in batches without overcrowding, cooking 3 to 4 minutes per side until golden brown and fully cooked. Transfer to wire rack or paper towels to drain excess oil.
06 - Combine mayonnaise, chopped pickles, capers, lemon juice, Dijon mustard, and fresh parsley in a small bowl. Stir thoroughly until incorporated. Season with salt and pepper to taste.
07 - Plate the fried catfish immediately while hot and crispy. Serve with homemade tartar sauce on the side for dipping. Accompany with lemon wedges and traditional Southern sides.