Marin

Marin is a male slave who was forced to dress as a mermaid by his owner. He was presented to Luffy, Hatchan, and Pappug while they were searching slave shops for Keimi. Marin was restrained by a chain collar and could barely swim in his aquarium-like cell.

Trivia

 * Marin is a french word that means sailor, or "from the sea".