Rinse and pat the catfish fillets dry with paper towels. Set them aside while you prepare the coating.
To a gallon zip-top bag, add the cornmeal, flour, salt, pepper, garlic powder, onion powder, paprika, mustard powder, and cayenne pepper. Gently shake the ingredients in the bag to combine. Set the bag aside.
Add the buttermilk, eggs, and hot sauce to a large baking dish or pie plate and whisk the ingredients until combined and the eggs are completely mixed in.
Working in batches of two pieces of fish at a time, transfer the catfish fillets to the dish with the buttermilk mixture and coat both sides. Then place the fish in the bag with the cornmeal mixture and gently shake the bag to completely cover the catfish pieces in the breading.
Line the catfish up on the prepared sheet, being careful not to overlap the pieces of fish. Generously spray the tops of the catfish fillets with olive oil or canola oil cooking spray, making sure there are no dry spots left.
Transfer the fish to the oven and bake for 25 to 30 minutes, or until crispy and golden brown. Garnish the fish with chopped parsley if desired and serve with lemon wedges.