The strongest Merfolk in one piece

Important takeaways

• Merfolk are genetic relatives of fishmen, both of whom are subject to historical oppression and slavery.
• Strong sailors, like Hyouzou and Aladine, can hold their own in battle.
• Shirahoshi, is probably the most powerful mermaid, due to it being an ancient weapon.

More people is a somewhat niche but active species within One Piece. They are genetic relatives of Pisces men, with the main difference being that Pisces' fish-like features are more prevalent on top rather than below. Like fishmen, sailors are also biologically compatible with humans, as the three races have a deeper connection to the ancestors.

Nevertheless, historical oppressive attitudes, as well as sailors being highly valued slaves, mean that a majority of them are forced to stay underwater. Even so, it has been shown that some sailors are perfectly capable of fighting for themselves. Here are some of the strongest merfolk shown in One Piece to date.

5 Hyouzou

Officer/hired sword of The New Fish-Man Pirates

• Debut: Chapter 607 (Manga), Episode 527 (Anime)
• Species: Blue-Ringed Octopus Merman

Hyouzou was once considered the strongest swordsman on fish-man island. He was particularly scouted by Arlong, but the pair's partnership could not solidify as Arlong was unwilling to pay for his services. Hyouzou claims that it is for this reason that Hatchan, a squid-fishman also skilled with the sword, was part of the Arlong Pirates instead.

Hody Jones learned from Arlong's mistake and was willing to pay Hyouzou. The sailor was ambivalent to Hody's ideals, but acted as an officer because he was paid to do so. He is shown to be fast enough to block Luffy in his Gear 2 form and can take out many enemies. Because he preys on a blue-ringed octopus, he can also secrete toxins. Hyouzou was ultimately no match for Zoro, a fact exacerbated after excessive energy consumption from steroids rapidly aged him into a frail old sailor.

4 Aladdin

First Mate/Doctor Of The Sun Pirates

• Debut: Chapter 620 (Manga), Episode 540 (Anime)
• Species: Goat's Beard Brotula Merman

Aladdin was once a slave along with his former captain, Fisher Tiger, and many of his crewmates. He is currently the only named member of the Sun Pirates to have both been with the crew prior to Tiger's death and to remain with them to this day, as most of his known crewmates formed or joined other pirate crews afterwards. When Jimbei was the captain, he became the second in command, and it is very possible that he may now become the captain due to Jimbei's own departure.

In addition to his medical training, Aladine is skilled in fish-man karate, able to fight the likes of Charlotte Oven, a renowned officer of the Big Mom Pirates. Like most of his kind, he is also a capable swimmer, although unlike some sailors, his body type allows him to be on land without additional assistance.

3 The Neptune Brothers

Princes of Ryugu Kingdom

• Debut: Chapter 609 (Manga), Episode 528 (Anime)
• Species: Shark Merman (Fukaboshi), Oarfish Merman (Ryuboshi) and Opah Merman (Manboshi)

Fukaboshi is one of Neptune and Otohime's three sons, and is next in line to the throne. Like his family, he is sincerely devoted to his mother's dream of peaceful relations with humans, even in the face of adversity from humans or fishmen. He is shown to be serious and dutiful in general, unlike his younger brothers, Ryuboshi and Manboshiwhich is a more comedic duo.

All three are quite strong, with the New Fish-Man Pirates needing to take energy steroids to surpass their abilities. Unlike their father, the three are still in their relative prime, with Fukaboshi in particular showing the ability to recover from his injuries quite quickly. That said, they were no match for the pirates once they consumed the steroids and relied on the Straw Hats and Jimbei to help them further.

2 Neptune

Ruler of the Ryugu Kingdom

• Debut: Chapter 611 (Manga), Episode 530 (Anime)
• Species: Coelacanth Merman

Neptune is the husband of the late Otohime, a beloved mermaid ruler who wished for peace. Neptune worked tirelessly to keep his late wife's dream alive, and is universally loved by his subjects. He is also capable of communicating with whales, a relatively rare skill for sailors. He primarily uses this to communicate with his giant house whale, Hoe, who also serves as a means of transportation.

Still in his 70s, Neptune is a powerful sailor, able to withstand attacks from Hody even after the pirate's consumption of energy steroids. That said, his age has caught up with him, to the point where even his physical stamina can be surpassed by overexerting himself in battle.

1 Shirahoshi

The princess of the Ryugu Kingdom

• Debut: Chapter 612 (Manga), Episode 531 (Anime)
• Species: Melt-white mermaid

Shirahoshi is the only daughter of Neptune and Otohime. She is known for her gigantic size, being larger than her mother and older brothers at less than a year of age. She is quite fragile, having spent most of her life in a locked tower and being spoiled by her family. Her fragility is such that Luffy specifically called her a crybaby when the two became acquainted. She needed him to protect her as she left her room for the first time in years.

While she tries to become braver as she joins her family for Levely, she is quickly captured by the world noble Charlos, who wants to enslave her. Nonetheless, the young mermaid was saved, thanks to some quick interventions by otherworldly noble Donquixote Mjosgard, along with Sai and Leo of the Straw Hat Grand Fleet.

Despite her currently vulnerable state, it is a real possibility that Shirahoshi is far more powerful than her relatives put together. This is because she is the ancient weapon, Poseidon, a trait she inherited from a distant ancestor. Poseidon's main asset is the ability to control and communicate with the Sea Kings, powerful beings that populate all known seas. They respond to her feelings and wishes, such as her wish for Luffy to get help, even though she didn't directly ask for their help. In addition to this fact, she could likely grow in physical strength if she wanted to, as her relatives are among the most powerful sailors in existence.