About 600,000 salmon smolts had to be killed following an outbreak in February of infectious salmon anemia at two land-based fish facilities in Nova Scotia.

Aquaculture Minister Keith Colwell said Thursday the two facilities are located close to each other, but wouldn't name them. "The virus is just in one location and they move fish from one facility to the other," he said.

The loss amounted to almost all of one company's fish stock, but wasn't as significant for the second.

There aren't any health concerns for humans as the virus only affects salmon, he said.

Colwell also said it's unusual to have this kind of outbreak on land-based facilities.

"It's a real serious loss for the two companies that are involved, they're small companies, so we're very concerned about that," Colwell said.

According to a statement issued by the province, the fish-farm operators reported a concern to veterinarians who then conducted testing. Once the tests confirmed the virus, the sites were quarantined.

The province said the virus is native to Atlantic Canada and was first detected here in 1996. Prior to these incidents, the most recent disease-causing version of the virus in Nova Scotia was in 2012 at a Cooke Aquaculture site in Shelburne County.

In 2016, there were at least four separate incidents recorded in New Brunswick.

Colwell said the province wouldn't provide operators with financial assistance as that's not permitted under regulations.

CBC News requested comment from the Atlantic Canada Fish Farmers Association, but it has not responded.