Lump On Neon Tetra... What Is It?

I've had these 5 neon tetras fish for 4 months and all of them are doing great and have had no troubles. However, about a month ago I noticed this lump on one of them. He's also a bit smaller than the other ones. I've treated my tank for parasites and bacterial infects if that were it, but the limo from the one neon hasn't disappeared so I was wondering if it's something else? The school is laid out with 1 female (she's the largest), three males that are slightly smaller than the female, and then the one tetra which is the smallest and has the lump. I've also run tests on my eater and everything is fine. Can you please help me out? I'll provide pictures of the fish. Thanks!

 

Maybe it is a female too? Or It could be a tumor . I don’t know that much about neon tetras but this is my best guess

 

It may be neon tetra disease, I've heard of them getting lumps from it. "The first sign is swimming away from tankmates. Affected tetras will also lose their neon stripe and develop spots or cysts on their dorsal fins." does this description fit?

If so, I've heard it is highly contagious and untreatable, so hopefully that isn't the case.

Edit: Otherwise, It may be a tumor as EBR55 suggested. As long as it doesn't grow and you fish seems to be behaving normally I wouldn't worry about it.

 

It doesn't look like a contagious disease to me.

I think I would just provide good care as you have been doing and let nature take its course.

It's possible that one problem can weaken a fish and lead to another disease.

If necessary you could euthanise, but I would personally let things run.

Does the fish appear to be breathing heavily or have it's mouth open a lot ?

 

It doesn't look like a contagious disease to me.

I think I would just provide good care as you have been doing and let nature take its course.

It's possible that one problem can weaken a fish and lead to another disease.

If necessary you could euthanise, but I would personally let things run.

Does the fish appear to be breathing heavily or have it's mouth open a lot ?

It does open it's mouth a bit more than the others, but it still swims with the school and it doesn't go to the top as if it's having trouble with air.

 

I've seen this before but don't know exactly what the problem is.

I suspect it involves an osmosis-regulatory problem.

I think the fish swells up because it retains too much water in its body.

I'm afraid when I've seen it before it has been the beginning of the end.

You've done well so far and this is not your fault. Neon Tetras are farmed and I've found that a lot of them are poor quality, faulty even.

This is because they are bred for profit and poor quality fish that would not survive in the wild are retained and are allowed to reproduce thus increasing the problem.

 

Is this going to affect my other fish? Or will it be okay to just let nature take its course?

I've seen this before but don't know exactly what the problem is.

I suspect it involves an osmosis-regulatory problem.

I think the fish swells up because it retains too much water in its body.

I'm afraid when I've seen it before it has been the beginning of the end.

You've done well so far and this is not your fault. Neon Tetras are farmed and I've found that a lot of them are poor quality, faulty even.

This is because they are bred for profit and poor quality fish that would not survive in the wild are retained and are allowed to reproduce thus increasing the problem.

 

Yes I would be inclined to just let things be.

You can always intervene if necessary e.g. to end suffering.

I don't think it will effect the other fish.

But you could take it out to be sure if you wanted peace of mind.