Pat the catfish fillets dry with paper towels and cut them into smaller portions if needed. Removing excess moisture helps the coating stick and gives the fish a crispier finish.

1. Prepare the buttermilk mixture.Pour the buttermilk into a shallow bowl and stir in the optional hot sauce. Place the catfish fillets in the mixture and let them soak for 15–20 minutes in the refrigerator. This adds flavor and helps the coating adhere.
2. Mix the coating.In a separate shallow dish, combine the cornmeal, flour, paprika, garlic powder, onion powder, cayenne pepper, salt, black pepper, and dried thyme. Stir until the seasonings are evenly distributed.
3. Coat the catfish.Remove each fillet from the buttermilk, allowing the excess to drip off. Press it into the cornmeal mixture, coating both sides thoroughly. Shake off any excess coating and place the fillets on a plate.
4. Heat the oil.Pour about 2 inches of vegetable oil into a heavy-bottomed skillet or deep pot. Heat to 350°F (175°C), using a kitchen thermometer to check the temperature.
5. Fry the fish.Carefully place the coated fillets into the hot oil in small batches. Fry for approximately 4–6 minutes per side, depending on thickness, until the coating is golden brown and the fish flakes easily with a fork.
6. Check for doneness.The thickest part of the catfish should reach an internal temperature of 145°F (63°C). Avoid overcrowding the pan, as too many pieces can lower the oil temperature and make the coating greasy.
7. Drain the fillets.Transfer the cooked catfish to a wire rack set over a baking sheet. Let excess oil drain while the crust stays crisp. Sprinkle lightly with extra salt, if desired.
8. Serve hot.Arrange the fried catfish on a serving platter with lemon wedges, tartar sauce, and fresh parsley. Add your favorite sides and enjoy while the coating is still crunchy.