| the aetiology, histopathology, and ultrastructural features of perianal erythema (red anus syndrome) in the european eel (anguilla anguilla). | the european eel (anguilla anguilla) is a critically endangered species. red anus syndrome (ras) is known to be associated with parasitic infections of the eel, particularly with anguillicola crassus, but the full range of causative pathogenic organisms has not been systematically investigated. here we examined the infective organisms and histopathological and ultrastructural features of seventy eels with ras. in total, nine different pathogens were detected in association with ras: pseudomonas ... | 2014 | 24608418 |