Rinse fish; pat dry. Cut in 8 pieces. In shallow dish combine cornmeal and 1-1/2 teaspoons of Cajun seasoning; coat fish with cornmeal mixture.
In 12-inch skillet cook fish in hot oil over medium-high heat for 8 to 10 minutes or until browned and fish flakes when tested with fork.
Meanwhile, thinly slice peppers, celery, and onion and combine in medium bowl. In small bowl combine mayonnaise, ketchup, remaining 1/2 teaspoon Cajun seasoning, and hot pepper sauce. Add 1 tablespoon mayonnaise mixture to pepper-celery mixture. Spread some of remaining mayonnaise mixture on cut sides of rolls. Place catfish pieces on roll bottoms. Top with celery mixture and roll tops. Pass any remaining mayonnaise mixture. Makes 4 servings.