Hotstuff is one of Cleo's tropical fish. In the episode, Dangerous Waters, Rikki got Cleo this fish as a replacement for Cleo's recently deceased fish, Pluto. Originally, Rikki bought Cleo a goldfish to replace Pluto, but Cleo could not accept the goldfish because she only collects tropical fish (AKA salt water fish). So, Rikki procured Hotstuff from the ocean as a mermaid. Barry Rollins saw Rikki with Hotstuff, and offered her a job to gather fish for a profit. Cleo named Hotstuff in honor of Rikki.