Preheat oven to 350º F. Evenly place catfish fillets in a 9×13-inch pan. Combine and spread black beans, corn, tomatoes and green beans over the catfish fillets. Melt one stick of butter, and pour over entire dish. Add remaining seasoning together, and apply evenly over entire dish. Cut smoked sausage into ½-inch slices, and spread evenly over dish. Spread sliced onion and potatoes over fillets. Sprinkle 1 cup of shredded cheese over dish. Bake for 45 minutes to one hour, or until the catfish fillets are flaky to the touch. Serve over a bed of rice.