In a large cast iron skillet (or frying pan) pour about 1/2 an inche of oil, or enough to cover your fillets. Heat the oil to medium-high heat (thats about 6-7 on the turn dial.
Heat your oven to about 200 degrees. Place a sheet pan with a wire cooling rack inside the oven. This is where you will place the cooked fillets to stay warm while you cook the remaining fillets.
While you heat your oil and begin putting the dry ingredients together ( see next step) pour the buttermilk into a large shallow dish. Then place the catfish fillets into the milk. The more they are covered by the milk the better.
Now, to mix the dry ingredients. In a shallow dish; mix the flour, cornmeal and all the spices together. You can add your own seasonings if you wish too.
Now 1 by 1 remove the catfish from the buttermilk and dredge them in the spice mixture. Make sure to dredge both sides of the fish and place in the hot oil. Once you have the pan full pay attention to the fillets you are currently cooking.
Continue cooking the fillets until they are golden brown and crispy. Now, once you have finished cooking the first pan full of fillets, remove them and place them on the cookie sheet with the cooling rack that you have sitting in the oven.
Repeat the above dredging process and cooking process until all of your fillets have been cooked. Once complete, serve them hot and with your desired sides.