To quote Wikipedia, "Ponyo" is:
"(Gake no Ue no Ponyo, literally "Ponyo on the Cliff"), is a 2008 Japanese animated fantasy film written and directed by Hayao Miyazaki of Studio Ghibli.

It is Miyazaki's eighth film for Ghibli, and his tenth overall. The plot centers on a goldfish named Ponyo who befriends a five-year-old human boy, Sosuke, and wants to become a human girl."