During field studies of the vegetation in the canal network of the Hydro-System Danube-Tisa-Danube in Serbia, in 2008, 2011 and 2012, populations of Cabomba caroliniana A. Gray 1837 were recorded. Cabomba caroliniana was not previously recorded in the aquatic vegetation in Serbia. It is a popular aquarium plant native to South America (Brazil, Uruguay, Paraguay, and northeastern Argentina) and, according to some authors, to southeastern United States. It was introduced into the rest of the USA, Canada, Australia, Asia (China, Malaysia, India, Japan), and in many regions of its new range it is considered an invasive and noxious aquatic weed. In Europe, it was found in the United Kingdom (introduced to England), Belgium, the Netherlands, and Hungary. Newly recorded populations in Serbia are restricted to the canals in Bačka. Populations are established only on two localities (Mali Stapar and Odžaci). [Projekat Ministarstva nauke Republike Srbije, br. III43002]