Acipenser huso, commonly known as the Beluga sturgeon, is a critically endangered species of fish found in the Caspian Sea and Black Sea regions. Synonyms for this species include Huso huso, the Great Siberian sturgeon, and the European sturgeon. Although these names all refer to the same species, they are used interchangeably depending on the region and context. Beluga sturgeon are prized for their caviar, which has led to overfishing and a significant decline in population numbers. Conservation efforts are being made to protect this species and restore its habitat, but it remains one of the world's most endangered fish species.