Otto is a character in A Fish Out Of Water. He is the fish bought from a pet shop by a boy at the beginning of the story. Mr. Carp, the pet shop owner, gives him feeding instructions. Unfortunately, the boy ignores these instructions, causing Otto to outgrow his fishbowl. This leads to the boy moving him into several different vases, ending with a bathtub, but Otto outgrows the tub, and the house begins to flood. The boy calls the policeman, who arrives and they find Otto in the cellar. When they finally have Otto out of the cellar, he then has no water. The policeman decides to call the fire department. The fire crew arrive and they take him to a local swimming pool where they drop him in, causing him to outgrow the pool. The boy calls Mr. Carp, who isn't surprised, but when he arrives, he notices how big Otto is, and dives in, returning the fish to his normal size. He doesn't say how he did it, but then tells the boy never to overfeed Otto again.