Section 1 | Biosecurity in Aquaculture

Ontario Aquaculture
Page 04 /

Biosecurity: Viral Hemorrhagic Septicemia in Ontario

Viral hemorrhagic septicemia (VHS) is endemic in the Great Lakes watershed in Ontario.


The virus affects a variety of fish species in Ontario and produces clinical signs such as1:

  • Pale gills and organs
  • Bloated abdomen
  • Bulging eyes
  • Hemorrhages (bleeding) on body and organs
  • Darker body color


While VHS causes only mild disease in farmed trout with no cases reported currently, it is still important to focus on prevention to limit its spread throughout the province. The disease can result in relatively high sickness and death rates in wild fish populations. For more information on VHS, visit the Government of Ontario’s information page here.


Source: OMAFRA

The Ministry of Natural Resources and Forestry has created 2 VHS management zones that all aquaculturists should know about.


Risk areas are stratified:

  • Red: highest risk — Great Lakes
  • Yellow: medium risk — areas of southwestern Ontario surrounded by the Great Lakes
  • Green: lowest risk — the remainder of Southwestern Ontario, including Guelph, Kitchener-Waterloo, Orangeville, Stratford, and Tillsonburg