Mixed parasitism induced experimentally in yellowtail, Seriola dorsalis reared in RAS: intensity and spatial distribution on the skin and gills

Abstract

Fish mariculture from the genus Seriola spp. can present high mortalities due to parasites. In Mexico, the mortality yellowtail Seriola dorsalis caused by parasites is low, and there are no reports of massive mortality events. However, as the aquaculture activity of yellowtail intensifies, parasites will be increasingly conspicuous. Therefore, the present study is an aim to know S. dorsalis ’s susceptibility to a monogenean infection mixed under RAS experimental conditions and their intensity and spatial distribution on the skin and gills. In this study, a parasitic mix induction was performed using two monogenean species such as Zeuxapta seriolae and Benedenia seriolae besides the Amyloodinium ocellatum , a dinoflagellate that was naturally presented. At the end of the experiment after 45 days, B. seriolae prevalence was 100% with a mean intensity of 122 parasites and showed a preference for the head and body of the fish. Zeuxapta seriolae prevalence was 100% with a mean intensity of 40 parasites preferentially found in the second branchial arch. In the case of A. ocellatum prevalence was of 100% with a mean intensity greater than 200 trophozoites per fish. The fish mortality reached 90% at the end of the experiment. During the infection, the fish weight decreased a 14% at the end of the experiment. Therefore, it will be necessary to carry out prophylactic and control strategies, to reduce the impact of these parasites under culture conditions.