Neobenedenia girellae (Monogenea) infection on cultured golden pompano Trachinotus ovatus in Zhanjiang, China

Neobenedenia species are pathogens of marine fish cultured in sea cages. From December 2017 to June 2018, a monogenetic trematode disease was observed on golden pompano cultured in floating net cages in Zhanjiang. The parasite was identified as Neobenedenia girellae based on both morphological characteristics and 285 rDNA or ITS1 sequence in this study. The life cycle of N. girellae was shown using clear microscope photos. The condition factor of golden pompano with body length ranged from 15.6 cm to 21.5 cm was significantly reduced post N. girellae infection. N. girellae tended to parasitize the tail fin post 28 days infection, as might be related to the significant low mRNA expression levels of complement C3 and C9 in tail fin in comparison with those in skin. The frequency distribution of N. girellae in the host population was aggregated distribution. The prevalence and mean intensity of N. girellae maintained high values from January to April in 2018, showing a negative relationship with water temperature. The study described at the first time biological aspects and infection changes of N. girellae on the fish golden pompano.