Morphological and molecular characterization of Contracaecum jorgei (Nematoda: Anisakidae) in five Neotropical freshwater fish species in Colombia

Larvae of the family Anisakidae occur in numerous freshwater and marine fish species. Although nematodes of the genus Contracaecum are widely distributed, little is known about their occurrence in fish in South America, particularly in Colombia. In this study, 257 specimens representing five Neotropical freshwater fish species— Andinoacara latifrons , Astyanax sp., Brycon henni , Parachromis friedrichsthalii , and Rhamdia guatemalensis —from the Porce River basin (Colombia) were examined for Contracaecum infection. Infective third-stage larvae (L3) of Contracaecum jorgei were identified using both morphological characteristics and molecular analysis targeting the mitochondrial cytochrome c oxidase subunit II ( cox 2) gene. Infection frequencies were A. latifrons (28.6%; 2/7), Astyanax sp. (38.3%; 23/60), B. henni (13%; 22/170), P. friedrichsthalii (21.1%; 4/19), and R. guatemalensis (100%; 1/1). To our knowledge, this is the first report of infective C. jorgei L3 in edible, commercially important freshwater fish species from Colombia. These findings contribute to the understanding of the parasitic fauna in Colombia and highlight the potential risks that this nematode may pose to aquatic biodiversity in the Porce River basin, which harbors 238 endemic fish species. • This is the first morphological and molecular characterization of Contracaecum jorgei in Colombia. • We conducted the report of C. jorgei in five Neotropical freshwater fish species in Colombia • This report expands the geographic distribution of the parasite Contracaecum jorgei to Colombia.