Combine cheese, butter, mayonnaise, onions, Worcestershire and hot sauce in a bowl and mix thoroughly. Poach catfish fillets in lightly simmering water for 4 to 5 minutes, or until thoroughly cooked. Gently take fillets out of water and set aside to drain.
Place fillets into lightly greased baking dish. Cover each fillet with 3 tablespoons cheese mixture, and place under broiler until mixture browns, about 2 to 3 minutes.
Carefully lift fillets from baking dish and place on individual plates, spooning pan juices over each serving. Garnish with fresh chopped green onions if desired.