Abstract
Purpose of Review In this review, we summarized the most recent findings on the partial and full genome and the phylogenetic structure of genomovars, as well as on virulence factors, vaccine development, and treatment methods of the two fish pathogenic bacteria Flavobacterium psychrophilum and F. columnare. Both species have a widespread distribution and are the causative agents of devastating diseases of both farmed and wild fish. For minimizing the impact of these infections, knowledge on biology and epidemiology of these pathogens is essential. Recent Findings Recent investigations have demonstrated a wide variability with regard to strains and genotypes. For both pathogens, new host species and geographic areas have been identified. For some isolates, a certain degree of host specificity could be demonstrated. Attempts have been undertaken to standardize methods for testing bacteria for resistance to antibiotics. Further, newly developed vaccines and a number of new treatment methods yielded promising results, but fully convincing and generally accepted prophylactic or therapeutic methods are not yet available. Summary In summary, despite intense research in the two species and considerable increase in understanding the host-pathogen relationship, there is still no generally applicable method to reduce the devastating effect of these bacteria species on farmed and wild fish populations.