In a statement issued by the company, chief operating officer Ross McCurdy reassured customers that they would not experience any interruption in supply, as the company's Nova Scotia plant has the capacity to pick up any shortfall.
ONC acquired the facility in Arcadia, Wisconsin in February in order to supply North American clients with its marine-derived omega-3 oils.
It was planned that the Canadian and European customers would be met by the Nova Scotia operation.
"Ocean Nutrition will conduct a thorough review of the event with a view to getting the facility fully operational as soon possible," said McCurdy.
Nine employees were working at the site at the time the fire broke out. All were evacuated safely, although two were treated for minor injuries.