Yucky is a rare Rainbow Swanfish who forms a crush on Daffney. He follows her around town as she gets ready for the Miss Junior Snorkland Beauty Pageant, even giving her back her purse. She gives him away to Professor Plankton, who takes him hostage. She and her friends rescue Yucky, who then turns into a Rainbowfish. He only appears in The Ugly Yuckfish.