Who Cooled Off the Piranha?

Piranha is a incorrigible ladies' man. So when he's found in a bowl of ice water, Sherlock concludes that the culprit must be a female who has felt betrayed by him. But which one? Stork, Mrs. Hippo or Gazelle? In the meantime, Hermione has lost her partner for the zoo's big dance contest. Sherlock proposes to replace him. But can he do it?