GREEN BAY, Wis. (WFRV) – Fisherman said the smell has been unbearable as thousands of dead fish show up along the shore of a nearly 40-mile stretch of the Fox River and Green Bay.

“It’s pretty nasty,” said Logan Geyer, a Green Bay fisherman. “I’ve just been seeing dead fish all across the Fox River. They’ve mostly been flowing from that way upstream. And mostly been catfish from what I’ve seen.”

DNR experts said in addition to those catfish common carp and freshwater drum are showing up dead too.

Jason Breeggemann, a DNR Green Bay Area Fisheries Biologist said, “Everything that we’ve seen from a water quality standpoint has been normal so we haven’t found anything that would attribute it to water quality but we aren’t certain of the cause.”

“It sucks for the fish and it sucks for me as a fisherman to catch them so it’s pretty bad,” said Geyer. “I kinda want to know what’s going on.”

“Over the last couple of days we’ve collected fish that we’ve taken to our veterinarians in Madison for pathogen testing that were either sick and still alive or freshly dead,” said Breeggemann.

The DNR said it will know more about the cause of this fish kill when testing is completed in Madison.