Mix together flour, curry powder, and soy sauce; coat bananas and fish with this; set aside. Heat oil in skillet. Stir-fry celery until crisp; set aside. Add butter to oil; saute bananas until golden, about 1 minute on each side. Sprinkle bananas with half of lemon juice; remove to serving dish. Saute fish in oil/butter mix until fish comes easily away on a fork, about 3 minutes on each side. Sprinkle with remaining lemon juice. Place on serving dish with bananas. Spoon celery over fish.