Bacterial cold water disease

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Bacterial cold water disease (BCWD) is a bacterial disease of salmonid fish. It is caused by Flavobacterium psychrophilum (previously classified in the genus Cytophaga),[1] a gram-negative[2] rod-shaped bacterium of the family Flavobacteriaceae.[3] The disease typically occurs at temperatures below 13⁰C, and it can be seen in any area with water temperatures consistently below 15⁰C.[4] Salmon are the most commonly affected species. This disease is not zoonotic.

Asymptomatic carrier fish and contaminated water provide reservoirs for disease.[5] Transmission is mainly horizontal, but vertical transmission can also occur.[4]

BCWD may be referred to by a number of other names including cold water disease, peduncle disease,[6] fit rot, tail rot and rainbow trout fry mortality syndrome.


The sweetfish which was infected with cold water disease

Fish infected with typical BCWD have lesions on the skin and fins. Fins may appear dark, torn, split, ragged, frayed and may even be lost completely.[7] Affected fish are often lethargic and stop feeding. Infection may spread systemically. Salmonid fish can also get a chronic form of BCWD[1] following recovery from typical BCWD. It is characterised by erratic “corkscrew” swimming, blackened tails and spinal deformities.[2][4]

In rainbow trout fry syndrome, acute disease with high mortality rates occurs. Infected fish may show signs of lethargy, inappetance and exopthalmos before death.[8]

A presumptive diagnosis can be made based on the history, clinical signs, pattern of mortality and water temperature, especially if there is a history of the disease in the area. The organism can be cultured for definitive diagnosis. Alternatively, histology should show periostitis, osteitis, meningitis and ganglioneuritis.[6]


Quaternary ammonium compounds[1] can be added to the water of infected adult fish and fry. Alternatively, the antibiotic oxytetracycline[2] can be given to adults, fry and broodstock. To prevent the disease, it is necessary to ensure water is pathogen-free and that water hardening is completed effectively for eggs.

See also[edit]


  1. ^ a b c "Bacterial Coldwater Disease (BCWD)-Flavobacterium psychrophilum" (PDF). Archived from the original (PDF) on 2013-12-03. 
  2. ^ a b c LaFrentz, B. R.; Cain, K. D. "Bacterial Coldwater Disease" (PDF). 
  3. ^ Nematollahi, A., et al. (2003). Flavobacterium psychrophilum infections in salmonid fish. Journal of Fish Diseases 26(10), 563–74. doi 10.1046/j.1365-2761.2003.00488.x PMID 14653314
  4. ^ a b c Starliper, Clifford E. (2011). "Bacterial coldwater disease of fishes caused by Flavobacterium psychrophilum". Journal of Advanced Research. 2 (2): 97–108. doi:10.1016/j.jare.2010.04.001. 
  5. ^ Brown, LL; Cox, WT; Levine, RP (1997). "Evidence that the causal agent of bacterial cold-water disease Flavobacterium psychrophilum is transmitted within salmonid eggs". Diseases of Aquatic Organisms. 29: 213–8. doi:10.3354/dao029213. 
  6. ^ a b Cipriano, Rocco C.; Holt, Richard A. (2005). Flavobacterium psychrophilum, cause of Bacterial Cold-Water Disease and Rainbow Trout Fry Syndrome (PDF). 
  7. ^ Schachte, John H. (2002). "Coldwater Disease" (PDF). In Meyer, Fred P.; Warren, James W.; Carey, Timothy G. A Guide to Integrated Fish Health Management in the Great Lakes Basin. pp. 193–7. 
  8. ^ Castillo, D; Higuera, G; Villa, M; Middelboe, M; Dalsgaard, I; Madsen, L; Espejo, R T (2012). "Diversity of Flavobacterium psychrophilum and the potential use of its phages for protection against bacterial cold water disease in salmonids". Journal of Fish Diseases. 35 (3): 193–201. doi:10.1111/j.1365-2761.2011.01336.x. PMID 22324343. 

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