Salmo peristericus, or the Prespa trout is a variety of trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

, a freshwater fish in the Salmonidae

Salmonidae

Salmonidae is a family of ray-finned fish, the only living family currently placed in the order Salmoniformes. It includes salmon, trout, chars, freshwater whitefishes and graylings...

 family. It is endemic to the Lake Prespa

Lake Prespa

Prespa is the name of two freshwater lakes in southeast Europe, shared by Greece, Albania, and Macedonia. Of the total surface area, belongs to Macedonia, to Greece and to Albania...

 watershed at the border area of Greece

Greece

Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

 and the Republic of Macedonia

Republic of Macedonia

Macedonia , officially the Republic of Macedonia , is a country located in the central Balkan peninsula in Southeast Europe. It is one of the successor states of the former Yugoslavia, from which it declared independence in 1991...

.

Four populations are known, one in the Agios Germanos

Agios Germanos

Agios Germanos, is a village in the Prespes Municipality in West Macedonia, Greece. Agios Germanos is located at an altitude of approximately 1,100 meters , on a hillside, part of the Varnoundas Mountains. It is from the Prespes lakes, which can be seen from a panorama location of the village...

 stream in north-western Greece, the others in the Brajcinska and Kranska rivers and the Leva Reka stream of Macedonia.

The Prespa trout is morphologically difficult to separate from other trouts of the region. Genetic data show it is close to and derived from the Adriatic lineage of brown trout

Brown trout

The brown trout and the sea trout are fish of the same species....

, and do not support a distinct species status. Nevertheless its protection as an ESU

Evolutionary Significant Unit

An Evolutionarily Significant Unit is a population of organisms that is considered distinct for purposes of conservation. Delineating ESUs is important when considering conservation action.This term can apply to any species, subspecies, geographic race, or population...

is justified regardless of the taxonomic status.