Fried Fish Cakes

1 cup chopped onion
1 cup chopped celery
1/2 cup chopped green pepper
1/4 cup melted margarine
1 to 1 1/2 lbs. fish fillets
1-8 oz. package herb-seasoned stuffing mix
1/2 cup self-rising flour
3 eggs, well beaten
2 tablespoons lemon juice
1 teaspoon salt
1 teaspoon dry mustard
1 to 2 teaspoons pepper
2 cup vegetable oil

Saute onion, celery and green pepper until tender. Combine all ingredients except vegetable oil, stirring well. Form into 3″ diameter patties and 1/2″ thick. Fry in hot oil until golden brown, turning once. Drain.