Gloom by a Triple-Threat is the 81 episode of the series and the 29 episode of Season Pure.
The Black Beauty Sisters create a new water demon called Napoleon Fish that hatch plans to catch Hippo as the bait to lure out the Mermaid Princesses, and Lady Bat, Lanhua and Alala is going to capture him.
The Black Beauty sisters dreamed that they almost beat the mermaid princess by let them drop their microphone, but Hippo pick up their microphones and transform and prepares to sing cause them begin to scared and fall down from the hammock they are sleeping . They decide to hatch up plans that won't fail, so they create a new water demon called Napoleon Fish that hatch up plans to capture hippo and use him as bait to lure out the Mermaid Princesses. They first plan to uses Alala's songs to attacted Hippo. It did not go as plan as Alala sing her song to her fans and was defeated by the mermaid princess easily. The second plan is Lady Bat using a ice sofa to attract Hippo by lying on it. It succeeded, but is failed again when the Mermaid Princesses appears and defeated Lady Bat.
- Hippo sings Legend of Mermaid for the first time.
- The Mermaid Princesses, Black Beauty sisters, and Napoleon fish were all shocked at Hippo's singing.