Intensive aquaculture sometimes provides conditions favorable for parasites that are not ordinarily found on culture fishes in the wild, and the use of introduced stocks sometimes introduces non-indigenous species to the habitat. When officially asked about the culture of Cobia Rachycentron canadum (Linnaeus) in Puerto Rico, the authors responded that it was unlikely to cause harm. It was assumed that a well-known culture facility in Florida would assure parasite-free stocks. Subsequent examinations of stocked juveniles surprisingly found parasites new to this fish. An outbreak of Slime-blotch disease, Brooklynella hostilis Lom & Nigrilli, 1970 (Dysteriida: Hartmannulidae) occurred in juvenile Cobia after they were shipped from Florida and stocked. This apparently represents a local parasite that took advantage of the weakened and/or crowded fish. The universal aquarium and culture superparasite, Marine Ich, Cryptocaryon irritans Brown, 1951 (Colpodia: Ichthyophthiriidae) was introduced with a shipment of juvenile Cobia from Florida. This may not be serious, since the parasite occurs worldwide, unless it represents a new strain to Puerto Rico. Marine Costia, Ichthyobodo sp. (Kinetoplastida: Bodonidae) was introduced into Puerto Rico with juvenile Cobia shipped from Florida. This parasite has caused some severe problems in aquaculture hatcheries in Hawaii and Texas after it was introduced with cultured organisms. Thus far, it has not caused any problems locally, but Puerto Rico lacks the marine hatchery facilities where such outbreaks would occur. The question of whether it is established locally will have to wait the development of similar facilities in Puerto Rico. These three species of parasites represent new host records for Cobia. The non-indigenous Ichthyobodo sp. represents new locality records for the tropical Atlantic, Caribbean, and Florida and Puerto Rico. Cobia mature more quickly in culture than in the wild and thus female Cobia apparently mature sufficiently before harvest to attract wild male Cobia to the net pen culture facilities. This represents a potential source of parasite and disease infection for the cultured and wild fish. Rev. Biol. Trop. 54 (Suppl. 3): 1-7. Epub 2007 Jan. 15.