Lamprey

Lampreys were a species of parasitic, leech-like eels.

Description
Lampreys had round sphincter-like orifices that were ringed with sharp teeth.

Biology
Lamprey injected some form of poison into the creatures that they attached themselves. While this poison was harmless to creatures other than fish, it imparted a severely sour taste upon the latter that many considered to be inedible.

Combat
Much like a leech or giant leech, used their mouths to fasten themselves to prey, from which they gradually drained blood.

History
The rivers that emptied into the Sea of Fallen Stars were plagued every few years by wide-scale attacks from preys. With fish traveling upriver, such as salmon, being the most affected. Over time many attempts were made to eradicate their species from the area, but none had proven successful.

Diet
These creatures primarily subsisted upon blood, draining it from larger species of fish. Unlike many parasitic creatures, they did not die with their host.

Habitats
Lampreys could be found in both fresh and saltwater environments, but were almost never encountered in shallow water. On Toril, they were particularly known to inhabit the Sea of Fallen Stars, the River Ashaba, and Dragon Reach.