From Aztec Mexico, an Ahuizotl is a water monster. It pretends to be a fish in order to lure humans closer to the water where it lives, only to grab the human using the hand at the end of its tail and drag him into the water to eat his nails, teeth, and eyes.

Ahuizotl Appearance

Size of a small dog
Slippery black skin
Monkey's face
Monkey's fingers
Human-shaped hand at the tip of its tail