The page on mandeans has been uploaded on Llurien.com. Some highlights:
Mandeans are one of the seven original humanoid species. They are amphibious. On land, they can breathe through their skins instead of lungs but that requires their skin to be moist. They do not have scales as some believe, but their skin is poisonous to consume. Salt water mandeans are called oceanic while fresh water are called river mandeans. Those who can breathe in both are called hydeans, as in hybrid mandeans.
Mandeans are slightly taller than most humans and have a sturdy, solid build, with large bones and solid muscle. Most have blue or green backs and white or light blue fronts. They sometimes follow a river to its source, living in mountain and subterranean lakes. Underwater settlements have great ecosystems. They use a spear or trident, or teeth and talons if disarmed. Mandean society is dominated by unity. They share and sacrifice for each other without jealousy or resentment. The needs of the many outweigh the needs of the few. Social standing is not recognized except for a minimal amount needed to govern.