Heat oven to 450° F. Spray the surface of a flat, nonstick baking sheet with cooking spray.
Beat the egg white in a shallow bowl until very soft peaks form. Do not over-beat.
Place flour on a sheet of wax paper.
On a separate sheet of wax paper, combine the cornmeal, panko and Cajun seasoning.
Cut catfish fillet so you have a total of 4 pieces. Dip the fish in the flour and shake off excess
Dip flour coated fish in the egg white, then roll in the cornmeal mixture.
Place fish on the baking pan, and repeat steps 6 to 9 with all the fish fillets.
Spray the tops of the fish fillets with cooking spray and bake for 10 to 12 minutes, until the bottom of the fillets are browned and the fish is sizzling. Remove pan from the oven and turn fish over.
Return fish to oven and bake about 5 minutes longer until fillets are browned and crisp.