Ponyo(2009)

Ponyo is a mischievous and adventurous little goldfish, who drifts away from the undersea home she shares with her father, the wizard Fujimoto, and hundreds of little sisters. Far from her home, she meets Sosuke, a 5-year-old boy who lives by the sea with his mother Lisa. Sosuke gently cares for his new pet and quickly wins Ponyo's heart. Ponyo's father, desperate for his daughter to return to their undersea home, uses his magic to bring her back, much to Ponyo's dismay. But Ponyo, ever the stubborn little goldfish, longs to return to her special friend. She magically transforms herself into a little girl and finds her way back to Sosuke's house where she and her friend embark on a series of adventures.