Case report: bacterial gill disease in goldfish Carassias auratus

Abstract

Three separate outbreaks of bacterial gill disease (BGD) were diagnosed in goldfish Carassius auratus L. purchased as food for larger piscivorous fish. Histologically, the fish from all outbreaks had large numbers of filamentous bacteria associated with the gill tissue. One outbreak displayed a m ~l d necrotizlng response to the bacteria, suggesting BGD is not inevitably lnamfested as a proliferative lesion. When the gill tissue was cultured on Cytophaga agar, large numbers of yellow pigmented bacteria were isolated from all fish. These were identified as Flavobacteriurn and Flexibacter/Cytophaga using biochemical test methods. Bath treatment of surviving fish with nifurpirinol halted further mortalities.