Monitoring antimicrobial resistance (AMR) in fish pathogens is essential for supporting sustainable aquaculture. In this study, susceptibility testing and genome sequencing were used to characterize the AMR profile of seven Flavobacterium psychrophilum originating from Danish rainbow trout farms (2019–2022). To establish epidemiological context and baseline virulence, isolates were also subjected to genome‐based Multi‐Locus Se...

Flavobacterium psychrophilum , the etiological agent of Rainbow Trout Fry Syndrome (RTFS) and Bacterial Coldwater Disease (BCWD), causes varying degrees of disease and mortality in salmonid aquaculture worldwide. Because its treatment relies on the use of antimicrobials, alternative interventions are of environmental and economic interest. As for other bacterial diseases, environmental factors like water parameters play a cruc...

A major bottleneck to the projected expansion of the aquaculture industry is disease outbreaks caused by bacterial pathogens. Fish diseases caused by Flavobacterium pathogens are persistent in salmonid aquaculture, and treatment is limited to antimicrobials, which contaminate the aquatic environment and promote antimicrobial resistance. Bacteriophages (phages) are viruses that naturally kill bacteria, and Flavobacterium ‐infec...

Vibrio vulnificus is a zoonotic pathogen that can cause death by septicaemia in farmed fish (mainly eels) and humans. The zoonotic strains that have been isolated from diseased eels and humans after eel handling belong to clade E (or serovar E (SerE)), a clonal complex within the pathovar (pv.) piscis . The aim of this study was to evaluate the accuracy of MALDI‐TOF mass spectrometry (MS) in the identification of SerE, using t...

Flavobacteria are among the most important pathogens in freshwater salmonid aquaculture worldwide. Due to concerns regarding development of antibiotic resistance, phage therapy has been proposed as a solution to decrease pathogen load. However, application of phages is challenged by the development of phage resistance, and knowledge of the mechanisms and implications of phage resistance is therefore required. To study this, 27...

During the winter of 2013 and 2016, several Croatian fish farms experienced mortalities in the fry of European sea bass, Dicentrarchus labrax . Affected fish showed abnormal swimming behaviour and reduced appetite, and death ensued several days after the onset of clinical signs of disease. Necropsy revealed pale liver, empty digestive tract, distended gall bladder, and hyperaemia and congestion of the meninges. Routine bacteri...