Bacteria, viz. Vibrio spp. all manifest similar symptoms. Can affect almost any marine, brackish and freshwater species.
Usually fatal in 2-3 days if untreated. Very contagious. Rapid treatment is vital if fish are to have any chance. Infection tends to stay in tanks for a long time.
DNA and RNA diagnostic references
Vibrio Related Diseases in Aquaculture and Development of Rapid and
Accurate Identification Methods.
From J.of Mar Sci: Research & Development Apr. 2012.
Shruti Chatterjee et al. Nat. Inst. Oceanography, Reg.Ctr.