I'm not saying your fish have VHS, but I recently bought false julii cory with VHS. I bought them Aug. 19th and they were just received at fish store.
I 1st saw a kind of big patch of pinkish coloration behind their front fins. Then, they sat on the bottom of the tank unless disturbed. I don't think they did any whirling. In about 36 hrs they went from normal to dead with big hemoragic patches like where a human's lungs would be. If it is VHS, it's a virus with no treatment and no cure (at present).
If you start observing what look like hemoraging patches on the dead fish. Then, I would suspect VHS and recommend euthanize all the rest and wait more than 14 days before adding living things to the aquarium. The virus dies after 14 days without a host.
As for coulmaris treatment. It is gram negative. So any antibiotic that kills gram negative will work. If you still have any cory or cat fish do not use salt. If you use an antibiotic make sure you remove the carbon in your filter.
Here is a good page on Coulmaris that suggests possible treatments:
http://www.myaquariumclub.com/columnaris-and-what-i-have-learned...-1689.html
Note: coulmaris can live for 32 days without a host.
BTW. antibiotics will mess up your beneficial bacteria. You will need to monitor all your water parameters daily.
(Friend of Bill W., One day at a time)
