1 lb. any fish fillets
1 c. mayonnaise
3/4 c. chopped onion
3/4 c. chopped, fresh mushrooms
3/4 c. chopped celery
Grated Cheddar cheese

Place fillets in a buttered, flat baking dish. Mix mayonnaise, onion, mushrooms, and celery. Spread over fillets. Sprinkle with cheese. Bake at 350 degrees for 20-30 minutes or until fish flakes. Do not overcook.