Sheshe and Mimi steal the two captured mermaids' pearls. Once the Black Beauty Sisters are used to power their evil microphones, they dare the four Mermaid Princess to fight them. Aqua Regina gives the Mermaid Princesses a new song. Hippo retrieves the "key" that allows him to transform into his true self – the Hippocampus. (Source: Wikipedia)

Aired on: 3/5/2004