The Epidemic Investigation of Turbot Reddish Body Disease Caused by Three Kinds of Pathogens

Turbot reddish body disease refers to the occurrence of reddish skin along fin base and vertebra on the blind side of farmed turbot(Scophthalmus maximus).It was reported that the causative pathogens of turbot reddish body syndrome(RBS)are diverse,which include bacteria,viruses and parasites,leading to a great challenge to the treatment of turbot RBS.In the present study,methods including light microscopic examination,selective cultivation of vibrio,electron microscopy observation(both negative staining and microtome section),cytopathic effect(CPE)examination and the specific PCR were used to detect and analyze the pathogens responsible for turbot RBS.The diseased fish were collected from different farms along Jiaodong coastal area in different seasons between March 2011and January 2012.The pathological symptoms were observed and the correlation among the outbreak of turbot reddish body disease,pathogens and aquaculture ambient temperature were analyzed.We found that(1)all the turbot RBS were not caused by pathogenic parasites;(2)bacteria(i.e.vibrio)caused turbot RBS when the ambient temperature was relatively high;and(3)either viruses or viruses and bacteria in combination caused turbot RBS when the ambient temperature was relatively low.Anemia of turbots and their grey gill filaments were the most obvious symptoms of bacterial turbot RBS,which was easily distinguishable from viruses turbot RBS.Our findings may aid to the effective monitoring of the outbreak of turbot reddish body disease,its rapid diagnosis and treatment and the healthy culture of turbot.