An estimated 600,000 salmon smolts were killed following an outbreak in February of infectious salmon anemia (ISA) at two land-based fish farms in Nova Scotia, reports the CBC.

Aquaculture Minister Keith Colwell said Thursday the two facilities are located close to each other, but he wouldn't name them.

The loss amounted to almost all of one company's fish stock.

Colwell 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," he said.