First report of the Asian tapeworm <i>Schyzocotyle acheilognathi</i> in the Colombian freshwater fish <i>Parodon magdalenensis</i>.

Abstract

The Asian fish tapeworm (AFT), scientifically known as <i>Schyzocotyle acheilognathi</i>, is a commonly encountered invasive parasite that has great relevance in freshwater ecosystems. This euryxenous cestode has a complex life cycle and includes a wide range of definitive hosts. It has also been reported in more than 300 species of free-living and farmed fish, amphibians, reptiles, and birds. Its remarkable pathogenicity leads to high mortality rates in infected fish, particularly among cyprinids. The environmental adaptability of <i>S. acheilognathi</i> has contributed to its global spread across continents, excluding Antarctica. In South America, <i>S. acheilognathi</i> has been reported in Brazil and Argentina. In this study, we examined 103 specimens of <i>Parodon magdalenensis</i>, a hyperendemic characiform fish species native to the Magdalena River basin in Colombia, and found a parasite prevalence in 32 of 103 specimens (31.07%). This study presents the first morphological and molecular characterization of the AFT in Colombia and its identification in a new host species (<i>P. magdalenensis</i>), supported by rDNA sequences from the 28S, 18S, and 16S regions.