In a medium bowl combine the cornmeal, flour and seasoning. Set aside.
In a small bowl, combine the cornstarch, baking powder, buttermilk and warm water.
Cut the catfish filets into thirds. Dip in the wet mixture and then dredget through the flour mixtures. Repeat.
Heat the oil to 350 degrees in a cast iron Dutch oven or deep fryer.
Fry the catfish until golden brown and crust is crispy.
Let cool on a paper towel or wire rack.