The Wisconsin Department of Natural Resources has identified what caused a recent fish kill in the Fox River and low Green Bay area. State scientists say the fish were diagnosed with severe cases of the bacterial disease columnaris. W-L-U-K/T-V reports the D-N-R estimates 99 percent of the dead fish found were adult channel catfish. The state agency started its investigation in mid-June after receiving multiple reports about the dead fish. Most were found downstream from the De Pere Dam and in lower Green Bay.