Fish-Men

Fishmen are one of two species that dominate the seas (the other being the Merfolk).

Statistics

 * Japanese Name: 魚人
 * Romanized Name: Gyojin
 * Translated Name: Fishmen
 * Dub Name: Mermen
 * Home island: Fishman Island

Biology
Appearance-wise, they are more "fish-like" than merfolk, looking like a cross between a man and a fish of the ocean such as an octopus, manta ray, or sawfish; however, they still have legs. They have their gills near their necks which only work when they are in water. On land they can breathe with their lungs like humans do. They are twice as strong as a human on land, and ten times stronger underwater.

Even though fishmen are part fish, they are still mammals and give birth to live young.

As was revealed during the Davy Back Fight arc with Big Pan Fishmen can also breed with Giants, producing a hybrid who has biological abilities of a Fishmen and a huge body of a Giant (but still smaller than, as related by Robin). Although never shown it's clear that Fishmen and humans can also breed the same way Merfolk and humans can breed.

Inter-species Relationships
Their view of life under the sea is dominated by their views that they should rule over all other fish in the sea. Despite this view, usually they get along well with the Merfolk who share the opposite view on life, however it is not unknown for Fishmen to take advantage of the Merfolk's nature.

A stereotypical Fishman ( this does not apply to all Fishmen) considers humans an inferior, weaker species. Because of their strength, they appear in One Piece on a regular basis.

Trivia

 * The kanji for Fishmen (魚人) is the reverse of the name for Mermen (人魚). They are often incorrectly referred to by fans, and the English dub made by 4Kids, as Mermen for that reason.
 * Originally Oda planned on introducing Fishmen as far back as Chapter 3. However, due to his editor he then put it back, ending up introducing the concept during the Arlong Park Arc instead.