|Primary Power||Fish-Related Abilities|
|Slave Price||Young Female: 70,000,000 |
Parted Female: 10,000,000
Merfolk (人魚 Ningyo, lit. Man Fish) are one of the two major races that inhabit the sea (the other being the fishmen). Both races seem to be ruled by the Great Knight of the Sea, King Neptune. They inhabit the Grand World, and, while they bear many similarities, the Merfolk of the Grand World are unrelated to the Mermaids found on Earth and Hōheikyū.
Appearance and Biology Edit
Like the mermaids and mermen of folklore, their upper half is that of a human while the lower half is that of a fish. Mermaids may walk normally on land as when they are thirty years old, their tails split into two. Like the fishmen, they are based on the different fish of the sea. Two mermaids of a similar species can also have very different looks.
As of now, it seems the mermen can keep more fish-features in the upper body, and it is also possible for merfolk to have webbing between their fingers like fishmen. Additionally, from what has been seen of obviously older mermen like King Neptune, it seems that the tails of male merfolk do not split with age like those of their female counterparts.
They are capable of breeding with humans, however, just one generation after the initial interbreeding, continuing to breed with humans may result in all merfolk features being lost. However, despite losing the merfolk features, they retain their ability to swim well. Humans, fishmen, and merfolk also share the same blood types. Unlike fishmen, merfolk do not eat meat and fish of any kind, aside from shellfish, so they remain primarily vegetarian.
Merfolk (mermen and mermaids) can have children with fishmen (fishmen and fishwomen). However, the child's race is up to chance between fishmen and merfolk. It is possible that there may be some hybridization, and grey area between the two races despite the clean separation. There are many merfolk who bear physical traits normally unique to fishmen. Furthermore, fishmen can sometimes demonstrate powers usually unique to merfolk.
Even with merfolk and fishmen in the same immediate family, the primary species (merfolk or fishman), subspecies (type of fish) and appearances may differ. The reason is that they still carry the genes of their ancestors, so the species is not determined only by the parents, but it can be any one type among all the species of the ancestors.
Mermaids split their tail when they turn thirty, however, this does not apply to their male counterparts as their tails will not split even after the age of thirty.
So far, all known merfolk subspecies have been real world species, and not any of Oda's made-up species.
While merfolk seem to vary as much as humans do, many of the male merfolks carry tridents. Merfolk are the fastest swimmers in sea, surpassing even the flying fish and fishmen. The mermaids have the ability to talk to fish and call out to them with a sound wave, which is apparently only audible to them. Despite this, however and for reasons as of yet unknown, mermaids are unable to talk with Sea Kings with the exception of an ancient mermaid princess of legend.
Despite the power of the Fishmen race, the Merfolk have a much stronger hold over Fishman Island. Mermen also seem to have developed a fighting style unique to their race (like Fishman Karate) known as Merman Combat which seems to involve the manipulation of water.