White Growths On My Cory (Pics Included)

[NeonBlueLeon]

Tank size: 20 gallons/75 litres
pH: 7.8
ammonia: 0 ppm
nitrite: 0 ppm
nitrate: ~10 ppm
tank temp: 82 F/28 C

Fish Symptoms (include full description including lesion, color, location, fish behavior):
White patches of growths on the side/underside of skunk cory.  Behavior was normal when I noticed the patches.

Volume and Frequency of water changes:
One a week, 40-50%.  Every other day 10%

Chemical Additives or Media in your tank:
No medications used yet.

Tank inhabitants:
7x Rummynose Tetras
1x Bolivian Ram
1x juvenile Creamsicle Molly
6x Skunk Cory

Recent additions to your tank (living or decoration):
All of the skunk cories but this one have been in the tank for a bit more than a week.  This one was added yesterday.

Exposure to chemicals:
API Leaf Zone (potassium & iron)
Seachem Flourish Excel (liquid carbon dioxide)
Seachem Prime

Photos:







My tank's stocking is a work in progress, and it's a little more crowded than I would like at the moment.  I ask you not to suggest a change in my stock (I have another thread for that) because that is not the purpose of this thread, and because I know the issues, and I'm working on re-homes.  Rather, I would appreciate help in ID-ing and treating the issue. 

Thanks for any help!

 

[Baccus]

The lumps look like a viral infection called Lymphocystis. The usual way it presents itself is cauliflower like growths on the skin or fins. The only way to be sure of this diagnosis is for microscopic examination.

 

[NeonBlueLeon]

Thanks, Baccus.  Follow-up searching on lymphocystis mentions that there is no way to conclusively diagnose it without taking a sample to a lab, but the symptoms match quite well.
 
I was fearing columnaris, but the cory is still alive.  He is in a quarantine tank, but it is causing him considerable stress as the QT is small and he is alone.

 

[star4]

There is no point in quarantining him, lymphocysits will be in the main tank and the stress of being separated will not really help, it usually will only affect one species of fish in the tank (I have delt with it a couple of times now with rescued fish) Lots of clean water, feed garlic infused foods and also soak food twice a week in Vitazin, this will not cure it, but it will help the fish keep up its strength while the virus runs its course. The main problem with this virus is secondary infections where the lumps are.