Osteinari, also known as Fish Folk, are humans descended from aquatic species of People. They normally live near to bodies of water, especially oceans or on islands, and sometimes live entirely in the sea. Osteinari have the ability to change their legs into a tail for easier swimming, and can have gills to allow them to breathe both air and water. Osteinari can also have a rudimentary ability to control water which requires practice to use effectively, but is still very weak compared to the magic of the People.
Osteinari generally have fins in place of ears (they can still hear just fine), scales in patches on areas of their body, markings on their skin, and other features dependent on what they're descended from. They take arid environments worse than other humans and deteriorate more quickly than normal when they become dehydrated.
Sometimes, on sunny days, they like to sunbathe, but only if there's water. Otherwise, it could be a death sentence for the Osteinari.