Cercopagis pengoi is a water flea native to the Ponto-Aralo-Caspian basin in South Eastern Europe, at the meeting point of the Middle East, Europe and Asia. It has spread from its native range and become invasive in some waterways of Eastern Europe and in the Baltic Sea. It has been introduced to the Great Lakes of North America, quickly becoming established and is now increasing its range and abundance. Cercopagis pengoi is a voracious predator and may compete with other planktivores. Through this competition, C. pengoi has the potential to affect the abundance and condition of zooplanktivorous fish and fish larvae. It also interferes with fisheries by clogging nets and fishing gear.