#1: Eel Folk
Hoping I am posting this correctly. 😉  Trying to step outside the female form with this one which is what I normally stick to. This creature is a bit outside the traditional merfolk form. Emitting voltage as an electric eel would and possessing eyes that can see in darker murkier waters these folk tend to stick to the deeper waters and caves beneath the surface.  Coloring and markings acts as camouflage  though they display a hint of color in their fins.