When I got home 4 of my eight girls were dead (this was only 18ish hours since I'd last checked on them and they were fine). I took the 3 live ones with obvious signs of columnaris and treated with a marycin 1 and 2 combo but all three were dead by the next morning. By the time I caught it it was too late.
I have one survivor who never showed any symptoms. Treated her with neomycin for 1 week (I think.. could have been two) as a precaution. She's healthy and thriving.
Here's the girl Janine was talking about. Neither of the other two had the necrosis but 3 of the dead ones did upon inspection.