Morphological and molecular characterization of <i>Contracaecum jorgei</i> (Nematoda: Anisakidae) in five Neotropical freshwater fish species in Colombia.

Abstract

Larvae of the family Anisakidae occur in numerous freshwater and marine fish species. Although nematodes of the genus <i>Contracaecum</i> 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-<i>Andinoacara latifrons</i>, <i>Astyanax</i> sp., <i>Brycon henni</i>, <i>Parachromis friedrichsthalii</i>, and <i>Rhamdia guatemalensis</i>-from the Porce River basin (Colombia) were examined for <i>Contracaecum</i> infection. Infective third-stage larvae (L3) of <i>Contracaecum jorgei</i> were identified using both morphological characteristics and molecular analysis targeting the mitochondrial <i>cytochrome c oxidase subunit II</i> (<i>cox</i>2) gene. Infection frequencies were <i>A. latifrons</i> (28.6%; 2/7), <i>Astyanax</i> sp. (38.3%; 23/60), <i>B. henni</i> (13%; 22/170), <i>P. friedrichsthalii</i> (21.1%; 4/19), and <i>R. guatemalensis</i> (100%; 1/1). To our knowledge, this is the first report of infective <i>C. jorgei</i> 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.