Tests have confirmed an infectious virus at a salmon farm on Vancouver Island.

The Canadian Food Inspection Agency says the IHN virus was detected in fish at farm operated by Mainstream Canada at Dixon Bay near Tofino.

The agency says all the fish have been destroyed and the farm will remain under quarantine until all pens, cages and equipment have been cleaned and disinfected.

The agency says the virus does not pose a risk to human health and is found in wild fish in the Pacific.

A quarantine was imposed earlier at another Mainstream farm at Bawden Point, also over fears the virus might be present.

A third quarantine had been imposed on a fish farm on the Sunshine Coast operated by Grieg Seafood, but later testing for the IHN virus came back negative.