Lancefield Group C Streptococcus dysgalactiae recently emerged as a catfish pathogen in the US. Reports from hatcheries suggest S. dysgalactiae causes substantial broodfish loss. We aimed to develop a challenge model and evaluate vaccine efficacy against S. dysgalactiae in juvenile channel catfish ( Ictalurus punctatus ). Three S. dysgalactiae (14–1, 14–24 and 14–25) isolates were tested for virulence. Intracoelomic (IC) injec...

Lancefield serological group C Streptococcus dysgalactiae (GCSD) is an emerging cause of fish disease worldwide, largely associated with mariculture in Asia. In the United States (US), GCSD had been a pathogen of minimal concern for fish, but recent cases indicate a putative emergence in wild and cultured freshwater fish populations in the Americas. The current study discusses three novel cases of GCSD‐associated streptococcos...

Columnaris disease, caused by columnaris‐causing bacteria (CCB), affects cultured and wild freshwater fish worldwide. Belonging to the phylum Bacteroidota and the family Flavobacteriaceae, CCB are gram‐negative, yellow‐pigmented bacteria that are presumed ubiquitous in freshwater habitats. Since the first report of the disease in 1922, growth and survival, pathogenesis, and transmission of these pathogens have been intensely r...

Channel catfish ( Ictalurus punctatus ) and Nile tilapia ( Oreochromis niloticus ) are two aquaculture species of great importance. Intensive production is often hindered by poor growth performance and disease mortality. The aim of this study was to evaluate the potential of a commercial fermented yeast product, DVAQUA, on channel catfish and Nile tilapia growth performance metrics and disease resistance. Channel catfish and N...

Biofloc technology is a rearing technique that maintains desired water quality by manipulating carbon and nitrogen and their inherent mixture of organic matter and microbes. Beneficial microorganisms in biofloc systems produce bioactive metabolites that may deter the growth of pathogenic microbes. As little is known about the interaction of biofloc systems and the addition of probiotics, this study focused on this integration...

Channel catfish (Ictalurus punctatus) is the top species produced in US aquaculture and motile Aeromonas septicemia, caused by virulent Aeromonas hydrophila (vAh), is one of the most severe diseases that afflict catfish farms. Previously, vaccination of fish with extracellular proteins (ECP) of vAh was shown to produce a robust antibody-mediated immune response against vAh infection. In this study, we analyzed IgM transcripts...

The antimicrobial activity and mode of action of chitosan were evaluated against Streptococcus iniae , a pathogenic Gram‐positive bacterium of fish worldwide. Cell proliferation kinetics were examined following exposure to varying concentrations of chitosan. The action of chitosan on S. iniae was also investigated by measuring agglutination activity, conductivity, and extracellular and intracellular bacterial adenosine triphos...

Flavobacterium columnare causes columnaris disease of farmed and wild freshwater fish. Skin mucus is an important factor in early stages of columnaris pathogenesis, albeit little studied. Our objectives were to (a) characterize the terminal glycosylation pattern ( TGP ) of catfish mucus, (b) determine the growth of F. columnare in formulated water ( FW )‐containing channel catfish ( Ictalurus punctatus ) or hybrid catfish ( Ic...