en Ecology Ecology پژوهشي Orginal research papers A new non-native ctenophore species, <em>Beroe ovata</em>, was recorded for the first time in the southern Caspian Sea on 13 November 2019 during a regular plankton sampling program. Considerable aggregations (1-5 individuals/m³) of <em>B. ovata</em> were found near an aquaculture site for fish cage, about 8.5 km offshore. The arrival of <em>B. ovata</em>, a non-native ctenophore predator for the Caspian Sea, has been much anticipated since the arrival of its prey, another aggressive ctenophore <em>Mnemiopsis leidyi</em> in the late 1990&rsquo;s. The adverse impact of <em>M. leidyi</em> has been devastating since its appearance on the Caspian Sea, causing unprecedented decreases in mesozooplankton biodiversity and biomass, resulting in a collapse of fisheries on small pelagics. The occurrence of <em>B. ovata</em> in the Caspian Sea is of significant interest for scientists, environmental managers and other stakeholders like fishermen since this new invader had already shown its ability to help in recovery of the fish stocks and ecosystem in whole in the Black Sea. Based on the outcomes of intensive field and laboratory studies in these neighbouring seas, we could suggest that the arrival of <em>B. ovata</em> also will result in the recovery of the Caspian Sea ecosystem. Ctenophore, Beroe ovata, Mnemiopsis leidyi, non-native species, Caspian Sea 1335 1342 http://jifro.ir/browse.php?a_code=A-10-4249-1&slc_lang=en&sid=1 A. Roohi Roohi_ark@yahoo.com 100319475328460046557 100319475328460046557 Yes Caspian Sea Ecology Research Center (CSERC), Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), P.O. Box 961, Sari, Iran. A. Kideys kideys@gmail.com 100319475328460046558 100319475328460046558 No Institute of Marine Sciences, Middle East Technical University, Erdemli, Turkey S.M.V. Farabi smv_farabi@hotmail.com 100319475328460046559 100319475328460046559 No Caspian Sea Ecology Research Center (CSERC), Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), P.O. Box 961, Sari, Iran. M. Rowshan Tabari rowshantabari@gmail.com 100319475328460046560 100319475328460046560 No Caspian Sea Ecology Research Center (CSERC), Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), P.O. Box 961, Sari, Iran. G. Finenko gfinenko@ibss.iuf.net 100319475328460046561 100319475328460046561 No Institute of Biology of the Southern Seas, Nachimov Ave. 2, Sevastopol, Crimea E. Arashkevitch shiganov@sio.rssi.ru 100319475328460046562 100319475328460046562 No P.P. Shirshov Institute of oceanology RAS, Nakhimovsky av., 36, Moscow, Russia S. Bagheri siamakbp@gmail.com 100319475328460046563 100319475328460046563 No Guilan Fisheries Research Center, Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), Anzali, Iran. H. Negarestan hosseinnegarestan@yahoo.com 100319475328460046564 100319475328460046564 No Islamic Azad University, Tehran North Branch, Tehran, Iran M. Rostamian rostamian2006ir@yahoo.com 100319475328460046565 100319475328460046565 No Caspian Sea Ecology Research Center (CSERC), Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), P.O. Box 961, Sari, Iran. H. Rostami hkr_rostami@yahoo.com 100319475328460046566 100319475328460046566 No Caspian Sea Ecology Research Center (CSERC), Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), P.O. Box 961, Sari, Iran. R. Pourgholam pourgholam38@gmail.com 100319475328460046567 100319475328460046567 No Caspian Sea Ecology Research Center (CSERC), Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), P.O. Box 961, Sari, Iran. T. Shiganova shiganov@ocean.ru 100319475328460046568 100319475328460046568 No P.P. Shirshov Institute of oceanology RAS, Nakhimovsky av., 36, Moscow, Russia