Sahuagin

Sahuagin were a fish-like monstrous humanoid species that lived in oceans, seas, underground lakes, and underwater caves. Sahuagin spoke the Sahuagin language, though some were known to also speak Common and Aquan.

Physical description
Sahuagin were usually green skinned; darker on the back and lighter on the belly. Many had dark stripes, bands, or spots, but these tended to fade with age. An adult male sahuagin stood roughly 6 feet (1.83 meters) tall and weighed about 200 pounds (91 kilograms). Sahuagin were highly fish-like, with webbed feet and hands, gills, and a finned tail. There was additional webbing down the back, at the elbows and, notably, also where human ears would be.

About one in every 216 hatchlings possessed four functional arms. These four-armed mutations were usually black, fading to gray in color. While sahuagin usually killed off defective hatchlings, they allow these to live.
 * Mutations

If a sahuagin abode was near a sea elf community or was frequently visited by a sea elf, a strange mutation occured within the sahuagin clan. About one in every 100 hatchlings would have appeared to look like a sea elf with greenish-silver skin and green or blue hair. These mutants were called malenti. Malenti were shunned by the clan as whole, but were protected by the clan's ruler and raised as spies by the clans best warriors and the priestesses.

Combat
Savage fighters, sahuagin asked for and gave no quarter. When swimming, a sahuagin tore with its feet, striking with its talons or a weapon. Spears and tridents tended to be their favored weapons. About half of any group of sahuagin were also armed with nets.

Society
Sahuagin were the natural enemies of aquatic elves and lizardfolk. Elves and sahuagin could not co-exist peacefully, and wars between them were often prolonged, bloody affairs that occasionally even interfered with shipping and maritime trade. Sahuagin tolerated the lizardfolk much more than they did the elves. Sahuagin had an only slightly less vehement hatred for tritons. Exactly why the two races hated each other so much was unknown.

They also hated the kuo-toa and the morkoth, though it was not unheard of for these races to ally.

Multiple births were frequent among sahuagin, and they dealt very harshly with offspring who were not robust or aggressive enough, eliminating them through compulsory fighting to the death between young sahuagin. Sahuagin seemed fixated on all aspects of consumption, and were eager to weed out anything they saw as weak or unworthy to compete for resources.

When going to war, Sahuagin followed a certain called the Laws of Battle. Sometimes however, a group of the sea devils would form a so-called Wild Hunt, which went on a frenzied rampage ignoring all rules.

Religion
Sahuagin worshiped Sekolah, god of sharks, as their patron deity and the father of their race. They also perceived him as the ultimate adjudicator and incarnation of punishment, officiating over an endless struggle between mythic figures. These figures were the hunter: "He Who Eats", and the hated: "It That Is Eaten", with the struggle between them reflected in every aspect of life. Because of this, sharks were seen as holy creatures to them, and dolphins were hated for their friendship with aquatic elves. The sahuagin made regular, living sacrifices to Sekolah by feeding the sacrificed being to the sharks that followed every sahuagin priest.