Flavobacterium columnare causing columnaris disease is an important freshwater fish pathogen worldwide. Saprolegnia ferax is generally considered as opportunistic pathogen and affects many wild and cultured fish. The present study describes the concurrent infection of F. columnare and S. ferax in Piaractus brachypomus, popularly known as pacu in India. During early winter, mortality was observed in cultured pacu. For investigating the disease, moribund pacu showing typical clinical signs, including namely erosion of fins, prominent discoloration of gills, and cotton-like growth on body surface were collected. The long bacterial rods were observed in gill squash preparation, whereas, wet mount of skin revealed aseptate hyphae. Histologically, extensive necrotic changes and loss of architecture of gill filaments, detachment of epithelial cells and loss of cartilaginous tissue with haemorrhages were observed in adjacent filaments. Importantly, an amplicon of 1193 bp was amplified in gills using F. columnare species-specific primers (FvpF1/FvpR1), suggesting infection with F. columnare. The sequencing of PCR amplicon revealed that F. columnare belongs to genomovar group II. Additionally, oomycete was isolated from the skin lesions, followed by ampification using primers ITS1/ITS4 and sequencing of amplicon of ITS region identified the oomycete as S. ferax. To our knowledge, this is the first report of coinfection of F. columnare and S. ferax in cultured pacu.