Cut off tops of green peppers; chop 1/2 cup, and set aside. Remove and discard seeds from bottoms. Parboil bottoms, and set aside.
Sauté chopped pepper, onion, celery, and garlic in butter in a large iron pot until tender. Add tomatoes, parsley, salt, and pepper; stir well. Cook, uncovered, 40 minutes over low heat. Add crayfish tails; cook 10 minutes. Stir in onion and rice. Cover; steam 5 minutes.
Spoon jambalaya into prepared green peppers. Place on individual serving plates; serve warm.