Neon tetra swelling at base of tail fin

[Haplix]

Hello,

While transferring som neon tetras to a new tank I noticed one of them has some swelling at the base of it's tail fin. The swollen area is the same bright red color as the area around it. I couldn't really notice it from the side but during transfer I looked straight down on them, see picture.

I haven't noticed any behavior changes and the fish seems fine. Tank parameters are also good.

Should I be concerned?

 

[Redshark1]

Not much to say. It could be slightly deformed or it may have a tumour or growth in that area. Its not something I've experienced with my fish. Hopefully it proves to be benign.