What races inhabit Kinyn? - The Sespin

The figure leapt over the waves, shining in the moonlight. The whole top half looked like a shapely woman, with flowing blue-green hair and scales covering her chest. Instead of legs she had a shimmering tail. She dove into the water, sending up a splash of water from her huge back fin. Nessa leaned out even farther, wanting to see her again.

--from The Healer and the Pirate

We've already spoken of the Elves and the Eaml. Here is the third of the four high races.

Of all the high races, the Sespin are the only ones who still guard their domain; the ocean. Silvery scales cover the Sespin from their fish tails to the napes of their necks. Both males and females have long shiny hair that can be any color found in the coral reefs. Their scale-like ears lay flat against their heads. The native tongue is sung, not spoken, and their voices are musical, often enchanting to sailors. On Earth they would be known as Mermaids or Sirens.

Before they fell, the Sespin were able to shift into human form. However, that ability has been lost. They have no innate magic but rely on potions and artifacts they’ve devised. They stay young until they reach about 100 years, when they start to age. Eventually, they plant themselves as coral on the ocean floor. The stories of the Savior have spread even into their undersea realms, though most Sespin instead serve the sea god Girgul.