Panda Cory with fin rot or something else?

[Rianyu]

HI guys, first time poster here and I'm hoping you guys will be more help than other places I've tried! Thanks in advance for your help, I am truly lost and I'm really scared of killing them by medicating with the wrong thing...

Water parameters
a) Temperature range. 73-75 F
b) pH. 6.6
c) Ammonia 0ppm
d) Nitrate 5ppm
e) Nitrite 0ppm
f) Water change frequency 30% every 6 days

Tank set up
a) Size. 30 Gallons
b) Substrate. Fluval Stratum
c) Filtration. Marineland Penguin 200
d) Furnishings. water wisteria, micro swords, amazon sword, scarlet temple and a large piece of driftwood + rocks
e) Other tankmates 13 neon tetras, 4 oto catsto cats
f) How long has it been set up? 2 months months

3. Symptoms / Problem description

It started with a batch of 3 new panda cories. I have 3 established in there since the first day of adding fish. They did very well and grew a lot! However after quarantining the new cories for a week (I know now I probably shouldve left them in the QT longer...) I put them in the main tank to join my original 3. One died suddenly after a week, I didn't think too much of it since there were no visible signs of disease and everyone else looked fine.

However another one showed symptoms eventually. Wasting and its tail was very curved, like a U. It was eating but very inactive otherwise and was easy to catch and put back in QT with the other new cory that started to look ill as well. Same curved tail, eating but not too active.

Second one died shortly after QT and now I have one. His fins are looking tattered too. I thought it may have been an isolated case with the new guys, but it seems to have either been in the tank or infected my original. I now have one of my original guys in the QT and I think I may have to add a third.

They are all showing signs of white edges on their fins, sort of like fungus.

4. Action taken (if any) See above. I am debating to transfer all of the pandas into QT. The neons and otos seem perfectly fine so far.

5. Medications used (if any) I am currently attempting treatment with API Tetracycline to see if it has any effect on the tattered fins.



These pictures are old. I can't take an updated one, but it shows the slight curve of the tail I was noticing. It's always curved like that if not worse...

[pleco_breeder]

Welcome to the site. I can't really tell from the pics, but doesn't look like a bacterial infection, so I'm doubtful of the effectiveness of tetracycline. I could be wrong, but better pic showing the fins clearly would be helpful in diagnosis.

Larry

[Rianyu]

Thanks.

I tried my best to get some clear pictures, I hope these will help. I noticed the red gills, did a water change and checked the water. Parameters are fine.