Neptune nonsense (1936)

Felix is feeding his various pets: a bird, two dogs, and a goldfish. But Annabelle the goldfish is unhappy; she's lonely. Felix sets out to catch her a friend. The fish drag him underwater. After a bit of searching, he finds a goldfish, but the fish cries for help, and Felix finds himself on trial before King Neptune. He's accused of wanting to eat the fish, but after he explains himself, Neptune gives him a fish from the fish orphanage, and everyone lives happily.