First occurrence of a parasitic isopod, Braga nasuta (Schioedte & Meinert, 1881) on ornamental fish in Europe

Isopods of the genus Braga (Cymothoidae) are haematophagous parasites of neotropical fish, causing anaemia, tissue damage and mortality. Braga nasuta, endemic to Brazil, has been reported from various hosts, including ornamental species exported worldwide. During a routine examination of imported cardinal tetra (Paracheirodon axelrodi, Schultz, 1956), the authors detected a fish harbouring an adult male isopod (6.21 mm long, 2.66 mm wide) attached anterior to the dorsal fin. Based on morphological identification, the parasite was B. nasuta. No secondary pathogens were observed in the affected fish specimen. Given the global trade in ornamental species, the introduction of B. nasuta into non-native regions underscores the importance of quarantine and parasite monitoring. Phylogenetic analysis has revealed that B. nasuta is most closely related to other freshwater parasitic isopods. While the potential ability of this parasite to establish populations in Europe requires further studies, vigilance is warranted to prevent potential spread and ecological damage.