On a plate, mix together the paprika, cayenne, thyme, chili powder, garlic powder, cumin, salt and pepper for the blackened spice mixture. Dredge the catfish fillets in the spice mixture and set aside.
Heat a large cast iron fry pan or saute pan over high heat until it is "white hot".
Add oil to pan. When oil begins to slightly smoke, add catfish fillets and cook on each side, about 2 to 3 minutes. Cook in batches, if necessary, and transfer cooked fillets to a preheated 200 degree F oven while cooking remaining fillets.
To serve, top each fillet with 1/2 tablespoon of butter and serve with lemon wedges.
Recipe courtesy of Guy Fieri, June 2008