Help!!! Fin issue. Not sure what this is.

[A. Atkins]

I can’t figure out what this red thing is on the tail fin of my Male Black Skirt tetra. I’ve tried google with no luck. He’s the only one in the tank with this issue and I’m not sure if it’s contagious or how to go about treating him. Any idea what it is??

[RachelElizabeth]

Ok, so I did some research and unfortunately I still have no idea what this is. Most growths occur on the fish's body, not the fins. 

That being said, (and this is just an educated guess!) growths, like tumors, are often not contagious. It still wouldn't be a bad idea to quarantine him if you have the room. 

You could try to treat with Maracyn, or just give it some time and see if it subsides. Not sure how long its been there at this point. 

[Keeg]

It is definitely a growth like what @RachelElizabeth, I would advise quarantine but I can't give you a 100% answer of what exactly it is. Fin rot is caused by bacterial and/ or fungus contrary to @Nooby said. Usually these blood sores/ growth are found on fancy goldfish, I dont know why, they just do. Is the fish covered in white dots like ich or is it just some floating stuff in the tank? 

To start off I would quarantine, and treat with maracyn like what @RachelElizabeth said above and keep the water clean. It should tackle it directly or start off in the right direction. Other than this, he looks pretty healthy so I would expect a full recovery. 

[Taco Playz]

That’s really weird. I would try Aquarium salt first then if that doesn’t work then I would go down the Maracyn route and see if that works. https://www.aquariumcoop.com/products/mardel-maracyn