Combine buttermilk and hot sauce: Whisk together buttermilk and hot sauce.
Marinade catfish: Place 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.
Make cornmeal mixture: Combine cornmeal and next 6 ingredients in a shallow dish.
Dredge catfish: Let fish stand at room temperature 10 minutes. Remove from buttermilk mixture, allowing excess to drip off. Dredge fish in cornmeal mixture, shaking off excess.
Heat oil: Pour oil to depth of 2 inches into a large, deep cast-iron or heavy-duty skillet; heat to 360°F.
Fry catfish: Fry fish, in batches, 2 minutes on each side or until golden brown. Transfer to a wire rack on a paper towel-lined jelly-roll pan. Keep warm in a 225°F oven until ready to serve.