Sprinkle fish with salt and pepper. Coil each fillet inside a buttered muffin tin or six-ounce custard cup. If necessary, trim top of each fillet to make it even. Drain crabmeat, remove fibers, and flake.
Sauté onion, parsley and celery in two tablespoons of the butter until tender. Remove from heat. Add crumbs, crabmeat and egg. Mix well and season with salt and pepper.
Spoon crabmeat mixture into center of fillets. Brush with remaining butter. Bake for fifteen minutes, or until fish flakes easily when tested with fork. Remove fillets carefully with two spoons.