A specimen of Prionotus punctatus was caught in Bahía Engaño, Chubut Province, Patagonia, Argentina. This extends the known distribution by 900 km and a 5.5° further south from its previous southernmost record. This record increases the number of species of the genus Prionotus and the fish diversity of central Patagonia. The presence of P. punctatus along with other recent reports of fish of tropical and subtropical lineages in central Patagonia adds new evidence on the ongoing tropicalization of the Patagonian Sea.