Emerald Cory Catfish - Large white area

[Polychronus]

Ok so I have an Emerald Cory Catfish that has recently become ill. It hides in the foliage all day, and only ever comes out to feed. When it started doing this, I noticed a white area near its upper back. It did NOT look like ich, but I could be wrong. I also noticed that it's fins started to tear. The only times it ever gets in a skirmish however is when my Bristlenose Pleco feels territorial.

I have a 20 gallon tank, and the pH is 7.0. It's been set up for almost 3 years now, and I have not had any ill fish for 6+ months. I change my water every week (about 5 gallons), and my fish are on a healthy diet. None of my fish are aggressive, except occasionally my Pleco.

My Cory Catfish is getting near the end of her lifespan (Will be 3 years old in August), and I want to know whether she is just dying from age or what she is infected with.

Here is what she looks like: Imgur

Thanks!
~~Poly

[Polychronus]

I also forgot to add that on the other side of her body is 3 smaller white areas along the lateral line

[coralbandit]

Up your waterchanges as cories are super sensitive to dissolved organics.
Looks a little like 1 of the 4 strains of Columnaris.
Fish Columnaris | Fungus & Saprolegnia | Treatment & Prevention

[Polychronus]

Ok thanks for letting me know. I couldn't find anything on what it might be on MANY websites. Obviously Fish Columnaris should be added to the standard disease lists.

[coralbandit]

What's your plan of attack?
Cories are know to be sensitive to dissolved organics in the substrate,salt,heat,some meds....
Possibly just upping water changes(even a couple large ones and sub vac) could help.
If the cory is alone that does not help as they are a very social creature .
Cories are one fish that definitely get healthier with clean water.
Genus Corydoras: general notes | The Skeptical Aquarist
Good info on your little guy!
Hope this all helps,love my cories(orange lasers)!
Columnaris is going to turn out to be this centuries "fish flu" IMO!!

[Polychronus]

I upped the heat, changed a large portion of the water, as well as cleaned the gravel. I definitely don't want this to spread to the rest of the school!


She is the biggest of my cories, and has produced the most young. I want to keep her for a little while more

[coralbandit]

Lower the heat!
75-72 will be best!
Not like ich,Colunaris gets stronger with heat(and clean water).

[Polychronus]

Good to know :0




I'm glad the heat hasn't been on for long lol