Quick Answer
Fish-Man Island is an underwater city located 10,000 metres below the Red Line, inhabited by Fish-Men and Mermaids. Long victims of Celestial Dragon slavery, they were liberated by the legendary Fisher Tiger and his Sun Pirates. Princess Shirahoshi reigns there as guardian of the Ancient Weapon Poseidon. The island becomes an ally of the Straw Hats during the arc spanning vols. 61 to 66.
Article written by the Wanted Store team — sources: One Piece manga vols. 1-110+ by Eiichiro Oda, Toei Animation anime, official SBS. Updated on April 26, 2026.
What is Fish-Man Island?
Nestled 10,000 metres beneath the ocean’s surface, directly below the Red Line, Fish-Man Island is one of the most spectacular locations in the One Piece universe. To reach it from Paradise or from the New World, pirate crews must traverse the Sea Current Whirlpool — a perilous vertical dive that only ships coated in a bubble hull can accomplish. The alternative is to cross the Red Line’s mountain continent itself via the submarine route of Mariejois.
The city extends beneath a colossal bubble dome, lit by luminous corals and bioluminescent algae. The capital is the Ryugu Kingdom, whose royal castle is built entirely of living coral. The architecture blends giant conch shells, millennial reefs, and spiralling towers adorned with pearls — a setting halfway between a fairy tale and a military fortress.
The population is divided into two distinct peoples:
- Fish-Men — approximately 70% of the inhabitants — have a humanoid appearance with features, fins, or scales borrowed from fish. Depending on their ancestral species, a Fish-Man can resemble a shark, an octopus, a blowfish, or a ray.
- Mermaids — approximately 30% — possess a human torso and a fish body from the waist down, in the manner of classical mythological depictions. Only females are Mermaids; males of this lineage are born as Fish-Men.
Although the island is officially a peaceful kingdom tied to the World Government, its history is marked by deep wounds — centuries of persecution and enslavement by the Celestial Dragons of Mariejois.
The Ryugu Royal Family
The Ryugu royal house has governed Fish-Man Island for generations. At its head stands King Neptune — a venerable colossus whose size and strength make him one of the most physically imposing characters in the series. Neptune was a close friend of Whitebeard, and his legitimacy rests as much on his warrior prestige as on his hereditary title.
His wife, Queen Otohime, was the island’s most courageous political figure. A small, boundlessly energetic mermaid, she devoted her life to a difficult and unpopular cause: campaigning for equality between Fish-Men and humans, and gathering signatures so that her people would be allowed to live on the surface. Her assassination — orchestrated in the shadows to block this reconciliation — remains one of the arc’s founding traumas and fuels the resentment of an entire generation.
Neptune and Otohime had four children:
| Name | Species | Role |
|---|---|---|
| Shirahoshi | Giant Mermaid | Princess, Ancient Weapon Poseidon |
| Fukaboshi | Shark Merman | Crown prince, military commander |
| Ryuboshi | Shark Merman | Second prince, fighter |
| Manboshi | Shark Merman | Third prince, fighter |
The three princes inherit their father’s physical power and protect Princess Shirahoshi with absolute devotion. For a long time they were unaware of their sister’s true secret: her ability to summon the Sea Kings, the world’s most gigantic marine creatures.
Fisher Tiger — The Liberator
In One Piece’s pantheon of heroes, Fisher Tiger occupies a unique place. This tall Fish-Man, his body covered in tattoos and his gaze fierce, is the founder of the Sun Pirates and one of the series’ most tragic figures.
The founding event of his legend is simple in its audacity: Fisher Tiger scaled the Holy Wall of Mariejois, infiltrated the city of the Celestial Dragons, and broke the chains of every slave he found there — Fish-Men, humans, and creatures of every species. This insane act, never accomplished before him, made Tiger a symbol of freedom for the oppressed throughout the world.
To protect these former slaves and continue fighting the oppression of the Celestial Dragons, Tiger founded the Sun Pirates. The name was a deliberate defiance: the sun — which Fish-Men never see from the ocean depths — became their emblem of freedom. The crew tattooed their members with a sun design over the infamous slave brand — the “Hoof of the Soaring Dragon” — symbolically replacing shame with pride.
Tiger’s death mirrors his life: uncompromising to the end. Mortally wounded in a Marine ambush, he refused the human blood transfusion that could have saved him. Not out of hatred for humans — Tiger despised hatred itself — but because his trauma as a former slave viscerally prevented it. He died asking that the truth of his story never be told to Jinbe, so as not to feed resentment.
Racism Against Fish-Men
The Fish-Man Island arc is one of the most explicitly political in One Piece. Oda addresses systemic racism, the legacy of slavery, and the dead ends of identity-based hatred head-on.
For centuries, the Celestial Dragons — descendants of the World Government’s founding kings, untouchable on pain of war — captured Fish-Men and Mermaids to use as slaves or display animals. Slaves were branded with the “Hoof of the Soaring Dragon” — the mark of the Celestial Dragon’s Hoof — a symbol of absolute ownership and denied humanity. This brand is visible on the shoulder of many characters freed by Tiger.
In the face of this institutionalised violence, two responses emerged on the island:
- Queen Otohime’s path: diplomacy, dialogue, and petitioning the World Government for legal rights for Fish-Men. A long, thankless path, mocked by part of the population who felt that extending a hand to one’s oppressors was a betrayal.
- The radical path: hatred in return, the refusal of any coexistence, the conviction that humans were enemies to be destroyed or dominated. This was the path chosen by Arlong, and then by Hody Jones.
Queen Otohime’s assassination — shot by a stooge manipulated by Hody Jones, who was himself manipulated by higher interests — perfectly symbolises how extremisms feed on each other, and how violence silences voices of reconciliation.
To learn more about the Celestial Dragons and their role in global oppression, see our article on the Celestial Dragons in One Piece.
Princess Shirahoshi — The Ancient Weapon Poseidon
Princess Shirahoshi is Neptune’s youngest daughter — a mermaid of extraordinary beauty and size, several times larger than most adult humans. Locked away since childhood in the Megalo tower to protect her from Hody Jones’s threats, she grew up isolated from the world, timid and easily frightened, yet possessed of a profound kindness and quiet resilience.
Her secret is momentous: Shirahoshi is the Ancient Weapon Poseidon, one of the three great weapons of mass destruction mentioned on the Poneglyphs. Poseidon is not an object or a mechanism — it is a living being, reincarnated from generation to generation, endowed with the power to communicate with and command the Sea Kings: those tentacled creatures of colossal size capable of destroying entire islands.
Were Shirahoshi to fully exercise this power without wisdom, she could trigger maritime catastrophes on a global scale. This is precisely why Joy Boy, in ancient times, engraved an Apology Poneglyph addressed to the previous Poseidon — a promise he could not keep, tied to a shared project linked to the Great Kingdom. This Poneglyph is located on the island and constitutes one of the major clues in Robin and the Straw Hats’ quest.
Our dedicated piece on the Ancient Weapons Pluton, Poseidon, and Uranus covers all of these legendary weapons in detail.
Arlong and the Radical Pirate Faction
Before becoming the antagonist of the East Blue arc (vols. 8–11), Arlong was a member of Fisher Tiger’s Sun Pirates. This imposing shark-man, with his oversized jaw and contemptuous gaze, genuinely believed in Tiger’s original cause: defending Fish-Men against oppression.
But where Tiger hated hatred itself and dreamed of a world without discrimination, Arlong took the opposite path. Tiger’s death, perceived betrayals by humans, and his own accumulated experiences transformed his grievance into racial supremacism. For Arlong, Fish-Men were not equals being unjustly treated — they were superiors whom inferiors dared to enslave.
By settling in the East Blue and oppressing the village of Cocoyasi (Nami’s hometown) for years, Arlong reproduced exactly the domination structure he claimed to fight — this time positioning himself on the oppressor’s side. His defeat at Luffy’s hands is one of the most cathartic moments in the series.
During the main arc of the island, it is Hody Jones who embodies this ideology at its most extreme. Captain of the New Fish-Man Pirates, doped on Energy Steroids, Hody never personally experienced the injustices he claims to avenge — his hatred is inherited, adopted as an identity, reinforcing Oda’s commentary on the cyclical and self-perpetuating nature of fanaticism.
Jinbe — The Bridge Between Peoples
If Fisher Tiger is the founding father and Arlong the tragic deviation, Jinbe is the fulfilment of the Sun Pirates’ promise. After Tiger’s death, he took command of the crew before becoming one of the seven great privateers of the World Government — a Seven Warlord — a position he used to maintain peace between the island and the surface world.
Jinbe’s relationship with Luffy was forged during the Impel Down arc and the Summit War at Marineford, where Jinbe refused to attack Whitebeard despite orders, then saved Luffy from emotional drowning after Ace’s death. He publicly resigned his Warlord title — an act that made him an enemy of the government — to remain at Luffy’s side.
During the Fish-Man Island arc, Jinbe plays a central mediating role. He is the living link between Tiger, Luffy, and Otohime’s legacy, and his final decision to join the Straw Hats as helmsman symbolises the synthesis of his entire story: neither Arlong’s hatred, nor defenceless naivety — but strength in service of coexistence.
To understand what it means to be a Warlord, read our article on the Seven Warlords in One Piece.
Find Jinbe’s Wanted Poster in our shop, or go for the complete Luffy crew pack featuring all the Straw Hats.
FAQ — Fish-Man Island in One Piece
- How deep is Fish-Man Island?
- The island is located 10,000 metres below the surface, directly beneath the Red Line. Crews must dive from the Red Line via a bubble air pocket, or cross the Red Line through an underwater tunnel.
- Who is Fisher Tiger and why is he important?
- Fisher Tiger is a legendary Fish-Man who infiltrated Mariejois alone, freed all the Celestial Dragons’ slaves, and founded the Sun Pirates. He is regarded as a liberating hero, even though his act triggered international fury. He died refusing a human blood transfusion.
- What is the Ancient Weapon Poseidon?
- Poseidon is one of the three Ancient Weapons in One Piece. Unlike Pluton (a ship) or Uranus, Poseidon is a reincarnated living being: the person who carries this power can command the Sea Kings. In the current arc, Princess Shirahoshi is that incarnation.
- What is the connection between Arlong and the Sun Pirates?
- Arlong was a founding member of Fisher Tiger’s Sun Pirates. After Tiger’s death, he drifted toward radical anti-human fanaticism, forming his own gang and establishing a regime of oppression in the East Blue — reproducing exactly the domination structure he once fought.
- Why was Queen Otohime assassinated?
- Queen Otohime campaigned for peaceful coexistence between Fish-Men and humans, gathering signatures for her people to gain the right to live on the surface. Her assassination was orchestrated in the shadows by Hody Jones to fuel hatred against humans and prevent any reconciliation.
- What is Joy Boy’s Apology Poneglyph?
- Joy Boy was a figure from the era of the Great Kingdom who made a promise to the previous Poseidon that he could not keep. He engraved his apologies on a Poneglyph preserved on Fish-Man Island — a key element of One Piece’s central mystery, linked to Luffy’s true identity.
- Is Jinbe officially a member of the Straw Hat crew?
- Yes. Jinbe officially joined the Straw Hat Pirates during the Whole Cake Island arc, having deferred his answer to Luffy across several arcs. He holds the position of helmsman and is one of the most experienced and powerful members of the crew.
