Columnaris disease in pet fish goes by many names: saddleback, guppy disease, cottonmouth, and camelback. It’s a highly contagious bacterial infection and one of the most common pet fish illnesses.

Columnaris outbreaks are a normal occurrence, especially in late spring and early summer when the water is warming up. “It is unusual to see a large die-off of wild, ...

Columnaris, according to a biologist sent to look at the area Monday, is believed to have killed the fish. Outbreaks of the disease happens multiple times a year in Michigan's lakes, ...