Rinse catfish fillets under cool water and lightly pat dry. Add the buttermilk to a shallow dish and coat the fillets in the buttermilk; set aside.
In a shallow bowl stir together the cornmeal, flour, garlic powder, and lemon-pepper seasoning. Allow excess buttermilk to drip off each filet then coat in the breading mixture, pressing lightly to ensure a thick crust. Allow to rest for 5 to 10 minutes.
Pour the oil into a deep cast-iron skillet to a little less than halfway full. Heat the oil over medium-high heat until the oil reaches about 350°F.
Fry in batches for 5 to 6 minutes on each side or until golden brown and cooked through. Drain on a wire rack over paper towels. Serve immediately with a squeeze of fresh lemon juice and my Dill Pickle Tartar Sauce.
