Skin, clean and cut in pieces. To 1/2 small cat-fish, allow 1 slice of ham, cut in bits. Cover these with 2 quarts of water, season with pepper and parsley, the ham supplies the salt, boil until the fish is tender, remove the back bones. Add to it a quart of boiling milk and 4 tablespoonfuls of butter cut in bits and rolled in flour. Stir in the beaten yolks of 4 eggs, boil quickly and serve while hot. The ham may be omitted, and the soup seasoned with salt. Other small fish may be cooked in the same manner.