Glowlight Tetra Bump

[raeven]

Hey guys I have a question I'm hoping someone might be able to answer.

We have a glowlight tetra who we're just noticing has a small lump directly under it's gills. It can be seen on both sides though is more prominent on the left. Unfortunately our camera seems to be busted right now, so I can't really take a picture, but I can say it's a little on the darker side compared to the rest of it's body.

Any ideas what this might be? And if so, should I be concerned that the other fish might get infected with this as well?

[Diztrbd1]

really best to post a pic, could be many things. I would definitely quarantine the affected fish in case it is something that may be passed on to the others