DOI: 10.1111/jfd.70228 ISSN: 0140-7775
A Two‐Step PCR Workflow Reveals Predominance of
Flavobacterium covae
in Ornamental Fish With Clinical Signs of Columnaris Disease
Pedro Henrique Magalhães Cardoso, Emy Yano, Simone de Carvalho Balian, André Pegoraro Poor, Kawany Miyazaki Araujo, Marianna Vaz Rodrigues, Andrea Micke Moreno ABSTRACT
Columnaris is an important bacterial disease of freshwater fish and is increasingly recognised as being caused by a species complex historically referred to as
Flavobacterium columnare
. A two‐step molecular workflow was applied to ornamental fish with clinical signs of columnaris disease from a multispecies commercial distributor operating a shared recirculating system in São Paulo, Brazil. Skin and fin lesion scrapings were Gram stained, and lesion‐derived tissue DNA was screened by ISR‐PCR for the columnaris disease complex. ISR‐PCR yielded the expected amplicon in 61/123 samples (49.6%) from 28 ornamental fish species. All ISR‐PCR‐positive samples were then analysed by multiplex PCR for species assignment. Group‐specific amplicons were obtained from 29/61 samples (47.5%):
Flavobacterium covae
in 27/61 (44.3%) and
F. davisii
in 2/61 (3.3%); no GG1 or GG4 amplicons were detected. The remaining 32/61 samples (52.5%) were not typeable by multiplex PCR. These findings provide baseline species‐level data and support combined molecular surveillance in multispecies ornamental fish systems.