From RocksfallWiki

This is what everyone (in Ashnabis, at least) knows about the hith:

The hith are a species of amphibious humanoids, about the height of a human. They sort of look like a salamander or newt. Their males and females look identical, or maybe they don’t have males and females. You’ve never seen a child hith but they definitely lay eggs. They are all sorts of different colours ranging from dull greens and greys to bright reds, oranges, and yellows. Some of them have gold eyes and others have dark black eyes, and some of the gold eyed ones have crests and ridges on their heads. Eye colour and the crests have something to do with how old or powerful they are. Their language, Hithaeli, sounds whispery and hoarse. You’ve heard that they worship the sun. Mostly they live underwater but they can breathe fine aboveground, and in some places they even live together with humans - such as the village of Pashas on the island of Ruur. Some humans, called hithkindred, have adopted hith customs and hith names. They use a special kind of barbed spear called a pfethe. They mostly eat fish and plants. Some of them have companion animals who they talk with. Hith don’t seem to be interested in fos and don’t use it to do magic.

Hithkindred, and of course the hith themselves, have access to more detailed information about Hith society.