The notorious but rare Giant tooth-fish (Th. "Hedpek") was a type of serrated salmon which could be found in some of the rivers feeding the bays of the Sinking Plain. The larger kinds of this species could reach a length of up to 2,3-3,5 feet and were known to attack cattle and even fishermen when angered or starved.
They were however believed to be have not originally been native to the northern bays of Endor or probably Middle-earth in general and may have been an invasive species, though it is unknown how they were introduced to the northern coasts or how they were able to survive there, as they only tolerated water down to 15 °C, temperatures only possible in very few areas of the north, where much of the heat of old Utumno remained and volcanic activity kept the waters warm and free of ice.One theory was that these fishes had been introduced by númenórean explorers, maybe identical with the mythical Zyedrahir-people (supposed ancestors of the Udahir) of the northern myths, and had been subjects to magical experiments and had been set loose, if intended or by accident remained unsolved.
Notes[]
The Loremaster (ICE Series) "Shade of the sinking plain" mentions "Piranhas" along with several other species unlikely or uncommon for a region quite similar to the east siberian sea.The description of these however more likely refers to the extinct Megapiranha or the Pacu, a type of serrasalmid fish closely related to the Piranha family.As invasive species Pacu so far have occasionally been found in colder climates , for example in Canada, Sweden, Russia.Occasionally Piranhas have also be found in parts of Siberia, however it was stated that these could only survive throughout the warm summer.