A specimen of the swimming crab Scylla serrata, a species native to the tropical Indo-West and South Pacific, is reported from Cartagena Bay, Colombia, in the southern Caribbean.It is the third alien decapod crustacean documented from the Caribbean coast of Colombia.Analyses of genetic sequences points to a northern Indian Ocean origin of this specimen.Presence of this specimen is considered an isolated case, most likely kept alive for human consumption on board ship and discarded in the Bay.