Red Area on Base of Fin on Corydoras

[KTshrimp]

Hello! I have 4 corydoras in a 20 gallon tank. I am doing a fish-in cycle as mentioned in some of my previous posts. The tank has been cycling for about a week now. Unfortunately, I have been out of town for a few days so I had someone else help out with the tank. I did daily water changes on Thursday, Friday, and Saturday, and then the person who took care of my tank did water changes on Sunday and Tuesday. After each water change I have been using Prime and Stability. The Ammonia still measures 0.

I am not sure if this is related to cycling at all, but all 3 of my female corydoras have a bright red mark right at the base of their pectoral fin. It is only on one side. It is very bright, like blood, and doesn’t look the same as the red blush spot they get when stressed. On one of them, it looks as if it might even be torn.

I also don’t know if this relates, but for extra background info, they have been breeding like crazy. Since I moved them into this tank, it is all I have seen them do. The mark is only on the girls, and the boy looks perfectly fine, so maybe something with their crazy breeding?

If anyone has any idea of what it going on, I would be so thankful for your help. I don’t want anything to happen with my precious cories!
I attached some photos I took of them- mainly the girl with the torn looking mark.
Thank you!

 

[DoubleDutch]

I think it is more or less the entire gill area that looks red. Corys are the worst fish to use in a fish in cycle cause they're quite sensitive to all nitrogyn-compounds. My guess indeed it has to do with traces of ammonia nitrites etc.

Just wondering (not judging) but what exactly is the use to do a fisn-in-cycle and use all kinds of products to get ammonia and nitrites to zero, though that's what needed to cycle the tank in the first place.

 

[KTshrimp]

I think it is more or less the entire gill area that looks red. Corys are the worst fish to use in a fish in cycle cause they're quite sensitive to all nitrogyn-compounds. My guess indeed it has to do with traces of ammonia nitrites etc.

Just wondering (not judging) but what exactly is the use to do a fisn-in-cycle and use all kinds of products to get ammonia and nitrites to zero, though that's what needed to cycle the tank in the first place.

Thank you for your reply! That is a good point, and I am not confident with an answer. I have never had to do a fish-in cycle and the products were recommended by some other Fishlore members. Mainly, I just wanted to keep the ammonia down while I was out of town so there wouldn’t be any unexpected problems.

 

[KTshrimp]

One of the red spots is now standing out from the corydoras. It looks kind of like a skin tag. What is wrong with them?
I did a water change earlier in case it was problems with ammonia but it has only gotten worse. Any help?

 

[skippyfish]

One of the red spots is now standing out from the corydoras. It looks kind of like a skin tag. What is wrong with them?
I did a water change earlier in case it was problems with ammonia but it has only gotten worse. Any help?

Too much trying to spawn maybe? What's the PH in the tank? FWIW, my corys are way more likely to try and spawn if the PH is below 7.0. (and the water is very clean, etc.)
I had to dose all of my corys for a bacterial gill infection of some kind when they first arrived, but if it's just the females, maybe not your situation?