Joint research by the HUN-REN Veterinary Medical Research Institute (HUN-REN VMRI) and the University of Copenhagen can help domestic catfish farming by establishing more effective treatment of gill worm disease. The findings of this rigorous investigation have been published in the reputable journal Scientific Reports.
The European catfish holds a significant position within Hungary's aquaculture industry, contributing significantly to the national fisheries and aquaculture production. Hungarian aquaculture production reached a total of 23,780 metric tonnes according to the Food and Agriculture Organization of the United Nations in 2020. Despite ranking sixth in aquaculture production, following carps and various other freshwater species, the European catfish faces a serious challenge. A parasitic flatworm with the scientific name Thaparocleidus vistulensis is able to infect and propagate in the gills of the fish, which may result in an infection level that threatens the health and welfare of the fish. This calls for the development of novel green and sustainable methods to control the infection. Researchers at the HUN-REN VMRI, in collaboration with the University of Copenhagen and supported by funding from Marie Skłodowska-Curie Actions, have recently reached a milestone towards this goal. They have provided significant insights by utilising molecular techniques and advanced scanning electron microscopy (SEM). The scientific community can now use this new detailed re-description of T. vistulensis. The precise diagnosis of the infection has been facilitated by the new molecular results. Moreover, the new knowledge acquired by the Hungarian researchers on the copulatory organs of the parasites may be important with regard to the control of the worm population in the fish farms.
Thaparocleidus vistulensis under the compound microscope. (Photo: Hazim Sajiri)
The present study has, for the first time, provided detailed molecular information about T. vistulensis, a parasitic worm found in European catfish. Through the analysis of its genetic code (DNA) and subsequent submission to a global database (GenBank), a unique sequence (OR916383) comprising 2694 base pairs has been identified, covering specific regions of the DNA molecule. Additionally, a family tree (phylogenetic tree) based on one of these DNA regions reveals a close relationship between T. vistulensis and another parasite called T. siluri, both of which exclusively infect European catfish. Moreover, the internal organ characteristics of T. vistulensis, particularly the male copulatory organ, provide valuable insights for future research on the parasite's evolutionary history and possible control.
SEM micrographs of Thaparocleidus vistulensis. (Photo: Hazim Sajiri)
This study represents a crucial branch of research focused on unravelling the biology of T. vistulensis, with the ultimate goal of devising strategies to control its reproduction, particularly within the European catfish farming sector.