Great Britain's Heather Frederiksen has had to settle for sixth place in the S8 50m freestyle final against a strong field.
The winner was United States's Mallory Weggemann who set a Paralympic record of 31.13 on her way to the gold medal.
Silver went to Australia's Elliott Maddison with a 31.44 and Jiang Shengnan posted a 31.55 for bronze.
One of the favourites, America's Jessica Long disappointed and finished fifth with a time of 31.71.