Weird Growth on Cory Dorsal Fin

[Wateveryousay]

I just recently noticed this weird abnormality on my emerald cory cat's back. Any ideas? All help appreciated, thanks again!

[mel_20_20]

It's pretty hard to see that very clearly... is it possible to get a pic of him from the side?

[Wateveryousay]

sorry wrong pic again haha

[Wateveryousay]

sorry wrong pic again haha

[Wateveryousay]

here it is

[mel_20_20]

I'm not sure but it could be lymphocystis. I'm adding an image of a cory with lymphocystis that looks a lot like the lesion on your fish's dorsal fin.

That does look like Lymphocystis, a rare virul disease in fish. It's not normally lethal, but can spread to others. Someone else may come along with more knowledge than me, but it does look a lot like lymphocystis.

I believe I would quarantine him, if you can, and wait to see if it goes away. I've heard that when it is in your tank it is contagious and other fish can contract it.

[mel_20_20]

It is possible that it is just a blister that formed over the fin ray, and it may just gradually go away by itself. I would be sure to maintain pristine water conditions.
Keep ammonia and nitrites at 0, and nitrates within safe limits, too, at 20 or below, and don't overheat him. You'll be giving his immune system optimum water conditions to do it do its job.

[Wateveryousay]

thank you for your help, i think its lymphocystis. ill quarantine him for a couple days and see what happens

[mel_20_20]

I agree that it sure does look like the same thing as the cory in the photo I uploaded, and that one does have lymphocystis.

Yes... that's good to seperate him for a bit. Maybe it won't be passed on to your other fish. I think it gets a foothold when there are water quality issues or any other reason or issues that might compromise a fish's immune system. A slight injury, scrape, or such, too, might invite infection by the virus.

So maybe excellent hygiene, i.e., pristine water conditions, may help prevent other fish from contracting it, if it is in your tank.