Abstract
This chapter focuses on five disparate groups of bacteria: Photobacterium damselae subsp. piscicida (formerly Pasteurella piscicida); the pseudomonads; members of the family Enterobacteriaceae other than Yersinia and Edwardsiella; Francisella and the atypical lactobacilli, including Carnobacterium maltaromaticum; and Vagococcus salmoninarum, which can be recognized as fish pathogens but about which there is not enough information to warrant separate chapters. Various other Gram-positive and negative bacteria that have been described recently as causing pathological conditions in fish were summarized briefly in this chapter.