Grung

As the great Sambar River winds its way down from the Voracious Hills and through the Verdant Expanse, it releases massive amounts of nutrients into its surroundings, which causes large collections of fish and crustaceans to swarm and school. Where the school meets the shore, you find the grung.
A race of amphibious humanoids, the grung have a complex social structure and even more complicated rules of etiquette that govern who is on the way up and who is tumbling down the large tower that is the grung cultural hierarchy. On the whole, they mainly want to be left alone, which is paradoxically why they signed the Accord of the Waters: if they have powerful friends, others are less likely to bother them.