Salmo peristericus, or the Prespa trout is a variety of trout, a freshwater fish in the family Salmonidae. It is endemic to the Lake Prespa watershed at the border area of Greece and North Macedonia.
Four populations are known: one in the Agios Germanos stream in northwestern Greece, and the others in the Brajcinska and Kranska rivers and the Leva Reka stream of North 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, and do not support a distinct species status. Nevertheless, its protection as an Evolutionary Significant Unit is justified regardless of the taxonomic status.
The Lake Prespa is located on the tripoint of North Macedonia, Albania, and Greece. It is a system of two lakes separated by an isthmus: the Great Prespa Lake, divided between the three countries, and the Little Prespa Lake, mostly within Greece. They are the highest tectonic lakes in the Balkans, standing at an elevation of 853 metres (2,799 ft).
The area contains three national parks: Prespa in Albania, Galičica in North Macedonia and Prespa in Greece. The largest town in the region is Resen in North Macedonia. In 2014, the Ohrid-Prespa Transboundary Reserve between Albania and North Macedonia was added to UNESCO's World Network of Biosphere Reserves.
The Great Prespa Lake (Macedonian: Преспанско Езеро, Prespansko Ezero, Albanian: Liqeni i Prespës së Madhe, Greek: Μεγάλη Πρέσπα, Megáli Préspa) has the total surface of 259 km2 (100.00 sq mi). The largest part of it, 176.3 km2 (68.07 sq mi) belongs to North Macedonia; 46.3 km2 (17.88 sq mi) to Albania; and 36.4 km2 (14.05 sq mi) to Greece.
To the south, the Little Prespa Lake has the total surface area of 46.8 km2 (18.07 sq mi), most of it in Greece, with the westernmost tip (4.3 km2 (1.66 sq mi)) in Albania.
The two lakes are separated by a 4 km (2½ miles) long and 500 metres (550 yards) wide isthmus on the Greek territory, carrying an embankment with a road connecting the village of Psarades. A short stretch of a canal connects the lakes on the western side of the isthmus.
