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Fin Rot?

2263 Views 7 Replies 4 Participants Last post by  J-P
I got four juvenile corydoras julii less then two weeks ago. I broke my own rule and did not buy them from my favorite, excellent fish store, but from another store where I occasionally buy supplies. They are far better than a Petco, but they do not have ideal conditions. But they had four healthy-looking, pretty young corys and I caved and bought them. I noticed that their dorsal fins looked a little ragged, but not enough to alarm me. Now they've gotten worse and I am worried. All four corys have a chunk missing out of their dorsal fin where the black spot is, all in the exact same place, all nearly the exact same size. I actually looked them up to see if this was some new fancy strain of corys with weird fins, but no. The holes are very gradually getting bigger. One fish has an exposed ray. All of their other fins are in pristine condition, and they are very active and eating lots of food. Except for their fins I would say the are in perfect health. None of my other fish are sick. One of my corys does have some missing barbels, but she might have come to me that way and they are growing back. Is this fin rot? How do I treat this? I'm attaching a picture, but it's not a very good one. All I had was my phone, and the cory didn't want to sit still and pose. Also, don't judge him by the color. I edited the color to try to provide enough contrast to make his dorsal visible.


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The store you bought them from had them mis-labeled, those are corydoras trilineatus. They are still awesome fish and one of my favorite corrys. I bought a group of them a while back with the same fin issues yours have. I just fed them well and let them settle in and after a couple weeks they re-grew their fins without any issues. I'd keep an eye on your water parameters though.
The store didn't have them labeled at all! (I told you, they aren't the best store). The clerk guessed julii, and I looked at pictures of them and agreed. Either way I'm happy. But I am concerned about their fins because they seem to be getting slowly worse instead of better.
I'd just stay on top of your water changes and feed them well and they should start healing soon. Fin rot comes from poor water quality. Also I would suggest you supplment their diet with some frozen or live foods.
I just bought some more Cory's from a big name pet store, they all had this. I don't think its fin rot. I think its damage from other fish and/or poor nutrition and poor handling. They seem to be healing, I still have them in QT.

+1 On frozen foods. Mine love frozen bloodworms.
Mine are fed frozen bloodworms, mosquito larvae and tubifex worms, but what they really love are the algae wafers. There's an algae wafer in the lower left of that picture that he was munching on when I got that picture. And my water usually tests fine. So I guess I should just wait and see?
doesn't look like fin rot... looks like a bite that is healing itself...

basically, the procedure is the same as the above mentioned: Keep that water quality pristine.

Possibly add just a bit of melafix just to help out a bit. Fin rot would be apparent on the dorsal and tail fins.
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