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 owner, gives him feeding instructions. Unfortunately, the boy overfeeds Otto, causing him 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 decides to call the policeman, who finds Otto in the cellar upon his arrival. He and the boy help Otto out of the cellar, but Otto ends up without any water. The policeman decides to call the fire department. The fire crew arrive and they take Otto to a local swimming pool where they drop him in, causing the fish to outgrow the pool. The boy calls Mr. Carp, who isn't surprised as boys always ignore his feeding instructions, but when he arrives, he notices how big Otto is, and dives in, returning the fish to his normal size. Refusing to say how he did it, Mr. Carp tells the boy never to overfeed Otto again. The boy finally remembers.