The Manic Mermaid is a mermaid who enjoys the same things as Marina: prepping her hair, table tennis, and the attention of Sharko. In her first appearance, she competes with Marina for Sharko to the point where the two mermaids throw other sea creatures at each other. Their fight ends when a red hat falls onto the Manic Mermaid, who then looks up to see a sea captain staring down at her. The captain thinks the Manic Mermaid is attractive, prompting her to smile nervously. The Manic Mermaid is craned up to the captain's ship and is not seen again until "Hair Story", in which she attends an opera with King Neptune. It is very likely she is the king's daughter because of this; additionally, they both have the same blonde hair and blue tails.
The mermaid looks similar to Marina, but has lighter skin, blonde hair, and a light blue tail. She wears a strapless blue bra, pink earrings and a pink hair tie.