In general, living humans are not what the Nix / Nixe seek, but it is believed they must perform one human sacrifice a year.
Description: Water spirits with varied forms. Mostly the form of a human body and a fish tail. Merman (Nix) or Mermaid (Nixe) as in the fairytale type creature.
This form of water sprite features in many different folklores including Norwegian, Scandinavian and English, but is commonly considered Germanic European. It mostly takes human form, but can also be horse and dragon-like. For the Germanic people these water spirits take the form of half human, half fish. The Nix can appear as a man, a fish and a snake. He can shape shift between them all. The Nixe are often beautiful women with fish tails. When in full human form their identity can be exposed by their dress hem, as it will be dripping with water.
This phenomenon was reported as early as 1180. It was said that the Nix and Nixe would lure people into the water, and ultimately, to their deaths. They are said to haunt vast areas of water in search of prey. In general it is thought that living humans are not what the Nix/Nixe seek, but that they must perform one human sacrifice a year.
In fairytales or pirate stories, the general idea of a merman or mermaid is that of a captivating figure seducing their chosen victim towards the water, and once they reach it, the merman/maid change their form into that of a menacing being and take joy in filling their victim’s lungs with the sea.
In days of old a common superstition attached to the Nix/Nixe was that children who were born with webbed feed and/or abnormally large heads were thought to be a Nix/Nixe in disguise, and would grow and copulate with the human race.
In hindsight, it is said that this whole mythical story was invented to keep children away from the waters edge to avoid drowning.