Consider the Sahuagin

Deciding how I want to do sahuagin - or shark-people in general for non-D&D settings - has been difficult, mostly because I haven't wanted to categorise them as inherently 'evil', but at the same time want to evoke the feelings of the official sahuagin and address the elements one would expect from a society of mutant hexapodal shark-men. Here's where I'm up to so far.

character concept by Giorgio Baroni

Sahuagin are predators at heart, and are fully aware of it. They haven't succumbed to bestial fury, but have instead built a culture around their instincts to hunt.

Their connection to sharks is one akin to man's first relations with wolves; not full domestication, but not outright hostility. There is a mutual recognition of kinship and respect, and the sharkfolk have over time developed the ability to manipulate sharks and their relatives to aid them in their hunts, or shoal in designated waters.

Different sharks are chosen for different purposes and regions. Tiger and lemon sharks aid in pack hunting; many a diver has been caught off guard by how tactical a sahuagin hunting pack can be. Hammerhead groups of ~100 individuals guard treasure and lairs, whilst white sharks are bargained with by leaders as guards and enforcers. A few tales speak of gargantuan, ancient sharks being called allies of the sahuagin, with the beasts coming and going for decades at a time, depending on what suits their fancy.