One Piece Season 1 Episode 31
The Worst Man in the Eastern Seas! Fishman Pirate Arlong!
The crew chases after Nami, who stole their ship, and Yosaku takes time during the trip to explain about Arlong and his Fishmen to Luffy and Sanji. Meanwhile, Usopp, Johnny, and Zoro arrive at the island Nami docked at.