Cory cats ill, possible columnaris?

[jackbailey]

Noticed on Sunday when I got in from work that two of my corydoras had these weird marks on their skin (I probably should've known something was wrong on saturday night when they wouldn't eat), but because it was Sunday everywhere had closed and I couldn't run to a LFS for a treatment or anything. 

 

My first thought was that it was ick but then it seemed to develop from small spots into more of a rash or blistering, woke up on Monday morning to two of the four corys dead and the other two had similar marks on their skin. I ran to my LFS and grabbed anti-bacterial and anti-fungal treatment (my thinking had moved onto it being something fungal because of the way it looked on the two deceased corys), i treated that on monday but it did nothing. One of them died overnight and judging by the other one it doesn't have long left. 

 

I've googled a bit and i think that it might be Columnaris based on the description here http://www.fishnet.org/sick-fish-chart.htm but i can't find any pictures of corys with columnaris that resembles this. So i was hoping someone here could confirm or point me in the right direction so i can treat the tank properly. 

 

First two pictures are of the remaining cory taken about twenty minutes ago, and the third picture is one I snapped on monday of one of them. 

[Shrimp Life]

The fish looks beyond saving . Try to quarantine all the time because I see they are in a gravel and tank with plants, and its extremely contagious. Adding any more fish to this tank will put them at risk. You'd have to sterilize the entire tank before using it for other fish.