2Place catfish in a single layer in a 13- x 9-inch baking dish; pour buttermilk mixture over fish. Cover and chill 8 hours, turning once.
3Combine cornmeal and next ingredients in a shallow dish.
4Let fish stand at room temperature 10 minutes. Remove from buttermilk mixture, allowing excess to drip off. Dredge fish in cornmeal mixture, shaking off excess.
5Pour oil to depth of 2 inches into a large, deep cast-iron or heavy-duty skillet; heat to 360°.
6Fry fish, in batches, 2 minutes on each side or until golden brown. Transfer to a wire rack on a paper towel. Keep warm in a 225° oven until ready to serve.