Diagnosis help please. Fin rot?

[Niton]

Hi all,
I have 8 neon tetra and all appear to be pretty healthy. However I've noticed one of them has a portion of tail missing.
They have a male and 2 female guppies as tank mates and I know they can nip a bit. Does the following look like an injury or could it be an infection of some kind?
Thanks in advance.

 

[Majsa]

A bit late but how’s the fish doing? Does the tail have white ragged edge, I can’t see it in the pictures? If so, I’d suspect it’s bacterial. I had a bad case of Columnaris 1,5 years ago, that didn’t end up well...But I also have a neon whose tail was split but it remained clear and healed by itself, although it took a good while.

 

[Niton]

Hi @Majsa, I wouldn't say the tail was particularly ragged. The fish itself is still happy enough. Feeding and shoaling with the rest. I haven't spotted anything that looks similar on any of the other tetra.

 

[Majsa]

That sounds good. If it’s not getting worse and the fish remains happy then it’s probably an injury which will heal with time and lots of clean water.

 

[Majsa]

Keep an eye on him though, if you see the tail edge gets milky or opaque, that is not a good sign. But considering it’s just one fish let’s hope all is fine.