1000 Tenge Balqash Alabugasy

Lake Balkhash is one of the few lakes on Earth with a documented split in water chemistry — the western half is fresh, the eastern half saline, separated by a narrow strait near Saryesik. The phenomenon has made it a subject of sustained scientific interest since Soviet-era hydrological surveys in the 1940s. Kazakhstan has drawn on this ecological anomaly repeatedly for its collector coinage programs, which since the 1990s have issued hundreds of commemorative silver pieces tied to regional geography and fauna.

The alabuga — a Eurasian perch native to Balkhash — has faced mounting pressure from introduced species, particularly carp and pike-perch, first stocked during Soviet fisheries programs.