(WFRV) – Two months after the DNR received reports of dead fish, officials provided the ‘likely’ cause of the die-off.

The Wisconsin Department of Natural Resources (DNR) announced that the fish that died off in the Fox River and lower Green Bay waters were diagnosed with server cases of columnaris. Columnairs is described as a common and widespread bacterial disease of freshwater fish.

It can cause yellow-brown or white lesions on the skin, fins and gills. Outbreaks of columnaris are reportedly normally, especially in late spring and early summer when the water warms up.

The bacteria does not infect humans or other animals.

The reports of dead fish started on June 18, which lead to the DNR doing a two-week investigation. An estimated 99% of dead fish found during the investigation were adult channel catfish.

Officials said it was hard to fish that were suitable for testing.

“Despite almost two weeks of responding to public reports and searching, it was difficult to find either sick or freshly dead fish suitable for testing. Most of the fish seen had been dead for at least a day,” said Dave Boyarski, DNR East District Fisheries Supervisor.

Most of the fish were found downstream of the De Pere Dam or in lower Green Bay. However, fish were reported as far north as Sturgeon Bay. Officials say it is not known where the fish originated from and strong currents and wind could have possibly pushed the fish north into Green Bay.

Even though this die-off seems to be over, the DNR still encourages the public to report sick or dead fish to local fisheries and biologists.