Mr. Carp is a character in the book A Fish Out Of Water. He is the owner of the pet shop, where a boy buys a fish, whom he calls Otto. He then gives the boy instructions on how to care for a fish, including feeding instructions: "Never feed him a lot. Never more than a spot! Or something may happen. You never know what." He later receives a phone call from the boy, who has ignored the instructions, and is not surprised as boys always ignore his feeding instructions. He heads to the swimming pool as quickly as possible, where Otto has outgrown the pool after being dropped in. Fortunately, Mr. Carp dives into the pool and takes Otto down with him, returning the fish to his normal size. Refusing to say how he did, he then tells the boy never to overfeed his fish again.