Put into the soup-pot the butter or drippings. Add the onion, carrot, and turnip. Fry them without browning, then add fish-bones, head, and trimmings, the celery, parsley, thyme, bay-leaf, tomato or lemon. Cover with water, and simmer them for an hour or more. Season with salt and pepper. Strain.
When this stock is used for soup, make a roux of one tablespoonful each of butter and flour, add a cupful of milk or cream, and add this amount to each pint of the fish stock.