The New Merman Pirates were a group of Merman-based pirates residing in Merman Island, though they also included several fishfolk, sea monsters, and enslaved humans. The New Merman Pirates were the most prominent figures in the long history of human/mermen hate over their hero Tiger Fisher's death. They carried on the legacy of Arlong, having established their crew based on Arlong's ideals. Like Arlong, they wished to make Mermen the supreme race and aimed to sink the humans into the ocean. With their defeat and arrest (save for the human pirates, who were allowed to leave freely), the New Merman Pirates are no longer active.
Their jolly roger consists of the Sun Pirates' sunny rim, with a crossed out decapitated person within - incidentally forming a double negative, further suggesting their irrationality.
Hammond and Hordy both bear the Arlong Pirates tattoos on the left side of the neck and left arm respectively, to signify their respect for Arlong. None of the crew members seem to be from the original Fishman Pirates.
Prior to their defeat, the New Merman had a grand total of 100,000 crewmembers; about 70,000 of them were mermen from the Merman District and 30,000 were human pirates that were captured and were used as slaves. However, 50,000 of them were taken out in an instant by a blast of Luffy's Conqueror's Haki and later the New Merman Pirates were breaking up during the battle when the human slaves were freed by Robin, who then retaliated against the New Merman Pirates followed by the lower echelons of the New Merman Pirates abandoning the crew after Hordy Jones's defeat and realizing that the officers were insane and were the ones truly involved with the death of Otohime; this was even enforced by the officers attacking them and Brook saving their lives, for which they were grateful.
They also had control of several giant sea monsters, all extremely large in size. The sea beasts alone (all boosted with the Energy Steroids drug) were enough to defeat Neptune's Army with ease (however, they were no match for the three princes). They used to control the Kraken as well until he befriended Luffy. As the bulk of the crew were mermen, most crew members are already ten times stronger than average humans and double that underwater.
However, their main source of strength (and ultimately what stripped the officers of their strength) came from the "evil drug" Energy Steroid that Hordy Jones stole from the Ryugu palace and then mass produced by Zeo to enhance their strength to greater levels. The crew's captain alone was enough to overwhelm an entire pirate crew with the help of this drug. Their willingness to use this drug, knowing the cost it brings, also shows they are willing to sacrifice their lives for their own cause.
They demonstrated high levels of brutality and were not above resorting to violence or murder. However, sometimes they also allowed their victims to live so that they can retell their encounters to others and spread their reputation and cause fear. Luffy himself acknowledged that their assassin Hyouzou was quite strong, because he was able to block one of Luffy's punches (although Zolo defeated him easily).
In comparison to the Arlong Pirates, they were much fiercer and a much greater threat; Jones himself claimed that this was due to them learning from Arlong's mistakes. Furthermore, the fact that they were willing to have mermen and captured human pirates as part of their crew means they were far more diverse tactically (although Arlong originally wanted to recruit Hyouzou, as well as forcibly taking Nami), but not culturally as the humans are used merely as shock troops and bullet sponges.
However, due to their heavy reliance on the Energy Steroid, it is unknown just how strong the main crew naturally was prior to becoming old, aside from their natural born strength. What is clear is that the officers needed these drugs to be more than a match for the Ryugu Kingdom princes, and based on a comment by the king they likely would be defeated without the drug's assistance. Furthermore, it seems that most of their 100,000 men have weak wills as half of them were taken down by Luffy's Conqueror's Haki, and the other 50,000 were spared purely for sport and could have easily joined their unconscious allies.
The New Merman Pirates also made an alliance with the feared Decken Vander IX captain of the Flying Pirates, who, with the aid of his aiming and tracking abilities, and the giant creatures at his service, makes for a powerful ally and asset for the crew. However, this alliance was voided when Decken sent the ship Noah after Shirahoshi and Hordy Jones attacked Decken.
After their defeat by the Straw Hat Pirates, the human pirates were therefore freed and returned to their old crews, reducing their size to 70,000 pirates, however these pirates (save for the leaders) were forced to do work under the supervision of the Neptune Army. After Hordy, Hyouzou, Decken, and the officers were imprisoned, the New Merman Pirates leaders became old and frail due to negative side effects of the Energy Steroids, stripping them of the power they naturally had forever and making them enemies no more.
The New Merman Pirates had four known named subdivisions:
- Artillery Squad (砲撃部隊, Hōgeki Butai): Composed of cannon wielders, they tried to take down Shirahoshi from afar. This squad was taken out by Brook.
- Iron Shell Squad (鉄の甲羅部隊, Tetsu no Kōra Butai): The members wield iron turtle shells as shields while attacking with blades. Some members of this squad were taken out by Zolo Roronoa, who used Black Rope: Dragon Twister to slice them up in a tornado. One of the members was also defeated by Luffy once he used Gum-Gum Bell after coating his forehead in Armament Haki. More members were also cut down by Hyouzou when he went on a rampage after an Energy Steroid overdose.
- Sea Urchin Spike Unit (ウニ衣トゲ部隊, Uni-Goromo Toge Butai): Composed of mermen dressed in spiked armor like that of a sea urchin, led by Harisenbon. They use the spikes on their bodies to skewer their opponents. The squad attempted to charge Sanji all at once, but he evaded them easily, causing them to harm each other.
- Deadly Venom Squad (猛毒部隊, Mōdoku Butai): Composed of mermen with extremely poisonous quills that can result in death with one prick. The squad was taken out by Franky.
Although referred as a pirate group, the crew did not actively pillage nor sailed the outer seas, and instead their actions and motives resemble more of a group of radical terrorists.
Arlong and his group's opinions of humans were driven by experiences which had been shared amongst the Sun Pirates and the events of their era. The New Merman Pirates are driven by the hate passed over from that generation to theirs and the suffering that had occurred in the previous generation is foreign to them. This is why, although they display the cruelty of the previous generation, they do not display the same set of ideals as Arlong and there is a contrast between how they react to each other and how the Arlong Pirates reacted. As such they hold no regard for their fellow mermen and are even willing to sacrifice their own crew members. They also differ from the Arlong Pirates in that, unlike the Arlong Pirates who took pride in their natural strength and heritage (which lead to them carrying out many fights which concentrated on just brute force), the New Merman Pirates have no concerns about what methods they use.
They appear to despise Queen Otohime and her ideals since they forced the citizens of Merman Island to step on her picture. However, even the crew members were shocked to learn that their captain was the one who assassinated Otohime ten years ago, aside from the officers, who already knew due to their close relationship with their captain; they went as far as to celebrate her death, claiming it was judgement by heaven. Also, Hordy and his officers are all willing to die for their goals, even if in failure, they believe that their deaths will leave a grudge that the next generation will pick up to continue their revenge; the lower echelons do not believe such, and will choose their own lives over this philosophy, which led the officers to force them to stay until death approaches. This appears to make them even more of an antithesis to Otohime, who tried to prevent hatred from being passed onto the next generation. By the end, the subordinates considered Hordy and the officers to be mentally unstable and monstrous, and abandoned their loyalty towards the crew, going as far as to claim they were forced into committing what they did.
- The New Merman Pirates action of attacking and burning homes of people who helped humans and focus on hatred is reminiscent of the Ku Klux Klan.
- The New Merman Pirates also resemble the New Black Panther Party, who are essentially a more extreme version of the Black Panther Party; a relation held between the Sun Pirates and the New Fishman Pirates.
- Their actions also show a clear mindset of terrorism, referring to their slaughtering of humans as a Holy war, even approving of actions such as suicide bombings, as long as humans are killed in the process.