My cory cat has a problem

[negative_tea]

I have four cory cats in a tank along with an assortment of other fish including a juvenille senegal bichir. One of my julie corys has an odd red bump next to his left fin. He seems to be moving fine. I noticed it last night. I do frequent water changes but did not sift my sand for about a week and a half. Last time I changed my water I sifted the sand and rearranged the driftwood. Now, it's three days later....

I'm curious if this is a problem caused by and ammonia burn or a wound caused by my sene. If it is caused by ammonia burn and the water has been recently changed what should I do to treat my sick Cory?

 

[negative_tea]

hmmm...I noticed this abrasion last night and by this morning...it has almost completely dissipated. There is still a bit of redness but nothing that looks too nasty. I think I'll Quarantine the Corys and then change them into a different tank. My Bichir is getting a bit big and it's possible he may have snapped at the corys....

Any disagreements?

 

[Lupin]

Doesn't sound like ammonia burn to me. What are the ammonia, nitrite and nitrate precisely? Do you have pics of the affected fin area?

Good call quarantining them though but cories in general are very sensitive to substrate bed especially if not vacuumed often. Bad bacteria produces quickly in the bed so it can contribute to their health issues.