Mix together spices in a dish. Spread olive oil onto catfish fillets. Spread spices onto catfish fillets. Set aside.
Fill smoker with hardwood BBQ pellets. Prepare smoker by placing 2-3 long sheets of aluminum foil along the bottom of the smoker element, underneath the rack, for easy cleanup.
Brush grill rack clean. Set smoker to smoke. Allow to preheat.
Place catfish fillets directly onto grates with skin side down. Set smoker to 350 degrees and cook for 15 minutes. OR 250 degrees for 45 minutes for a smokier flavor.
** Thickest part should reach 145 F. before removing, allow to rest 5 minutes before serving, cutting.