This race can only be selected when you first make your character at the moment. It is accessible through clicking on the right of the human option, though there is no arrow to actually click on, so it's more of a "hidden" race option even though the race is plentiful in content.
Fishmen will be the sole users of Fishman Karate when it gets released.
Fishmen are given multiple benefits that occur only when they enter the Ocean.
Players are able to change the Skin Color of their character during Character Customize when you start a new game. You're now able to change biological features like hair, etc.
2) Fishmen do about 2x normal damage when using melee moves in the Ocean
3) Fishmen are capable of surviving underwater indefinitely without losing stamina or air, but won't gain stamina over time underwater.
4) It has been confirmed by ShadeTheFallen that Fishman Karate will be available to Fishmen only, and will be created at a later date. Its power will be increased 2x when used underwater.
5) Eating a Devil Fruit will not take the speed or ability to breathe under water away the only speed decrease is that of rising to the surface. Fishmen however, will be unable to swim if they have eaten a DF in the future.