An investigation into a massive fish kill-off in Holter Lake that started around Independence Day, is still unresolved. Ron Aasheim of Montana Fish, Wildlife and Parks explains what researchers know so far.

"We got reports of a number of carp being dead in the water and as a result of that we did some testing, but it was really inconclusive," Aasheim said. "This was about a month ago now. The kill didn't appear to be caused by a bacteria or a viral pathogen, as the technical experts would say. The population looked to be a little stressed, it was likely a combination of factors such as aging, diet, water quality, maybe parasites. The good news is that it didn't appear to be caused by an infectious bacteria or a virus."

Aasheim says there were up to a hundred carp where killed in the lake. Although the mystery remains, Montana Fish, Wildlife and Parks has ended its investigation. Aasheim says instances like this are very rare.

Ron Aasheim: