Does my neon tetra have neon tetra disease?

I have 4 neon tetras in a 20 g with my nerite snail and betta. All the water parameters are great. One of my neons has weird color on one side of his blue stripe, making a part of it look dark blue. and whiteness on his tail, and a big cyst. Besides that, he’s just like all the others. He eats as much as them, maybe more, and schools with them and chases them, and they chase him. He’s just as fast as them, and acts completely healthy. He’s had it for about 3 or 4 weeks now. It hasn’t gotten worse since I first saw it. I’m seeing another tetra with a small bit of grey around his dorsal fin, and another one has a grey upper lip. Should I be worried? Is it neon tetra disease?

Please help! I’m worried, and I’m thinking if he’s been in the tank this long and no one else caught it, i won’t quarantine him. I’ll just treat him like the others. He might have a bit of fin rot, too, which might be from it. But maybe his tail is just growing back still from when it got nipped at. should I euthanize him? He’s an active fish who’s just like the rest except his condition. I’ve tried treating with api fungus cure, which didnt work. I don’t want to euthanize him! He doesn’t look close to death, just unhealthy looking. I’m going to try to act like he doesn’t have it, and if another gets it I’ll quarantine them both. But how do I treat it??

 

Please fill out the emergency template we can’t help you without this

 

What is the water volume of the tank?
How long has the tank been running?
Does it have a filter?
Does it have a heater?
What is the water temperature?
What is the entire stocking of this tank? (Please list all fish and inverts.)

Maintenance
How often do you change the water?
How much of the water do you change?
What do you use to treat your water?
Do you vacuum the substrate or just the water?

*Parameters - Very Important
Did you cycle your tank before adding fish?
What do you use to test the water?
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.

Ammonia: 0
Nitrite: 0
Nitrate: Around 5

Feeding
How often do you feed your fish?
2 times a day.
How much do you feed your fish?
enough to eat in 4 minutes.
What brand of food do you feed your fish?
tetramin and hiraki.
Do you feed frozen or freeze-dried foods?
no, but I’m going to try to.

Illness & Symptoms
How long have you had this fish?
3 months and 11 weeks.
How long ago did you first notice these symptoms?
about 3 or 4 weeks ago. Maybe more.
In a few words, can you explain the symptoms?
strange coloration, big cyst, whitening back half.
Have you started any treatment for the illness?
I tried api fungus cure.
Was your fish physically ill or injured upon purchase?
They were very small and thin.
How has its behavior and appearance changed, if at all?
the appearance had change from normal neon to this. Behavior hadn’t changed.

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)

I got 3 neon tetras after I restarted my 20 gallon. The tank was cycled, and they did well, so we went and got 2 more neons and my betta. Awhile after getting, (like, a long time after) I noticed a white cyst on the red part of one neons tail. I thought it was ick, and treated for ick. Then we noticed the neon‘s back half was becoming a white color, like clouds. some of his scales were pushed around, and it looked like some of the white was pushing past them.There was also a part of the blue in the tail that was a different shade from the rest of the tail. We treated with api fungus cure. Weeks go by, and he hasn’t gotten and better or worse. I do a water change, which i do weekly, and found one neon dead. It wasn’t that one, it was one that always seems to be chewing super fast. A short time after that, I can’t find this neon. I look everywhere, expecting to see a dead fish. Then look inside a fake plant, and there he was, all bend the wrong ways and stuck. You can imagine my surprise when I can finally inch him out and he goes back with the others, all deformed. his blue had turned yellow and he was swimming strange. The next day, he’s back to normal and his coloring is back. I removed that fake plant, of course. Where his coloring was off is now a dark blueish black color. He’s the fastest of my neons and doesn’t let them push him around. Besides the slight change in color, he looked the exact same as before he got stuck. It’s been weeks since, and he’s still the way he was when we first saw it.

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The school of Neons is pretty small. They maybe stressed and nipping at each other?
Bettas can be pretty sneaky as well, and may chase and nip the Neons.
The tumor could be an older wound?

 

This looks like False NTD, a species specific strain of Columnaris bacteria.
Meds don't really seem to work, but if treating treat with an antibacterial med. Perfect waterconditions and stressprevention could work.

 

This looks like False NTD, a species specific strain of Columnaris bacteria.
Meds don't really seem to work, but if treating treat with an antibacterial med. Perfect waterconditions and stressprevention could work.

Really?? I mean, I don’t want him to be sick, but this is good news compared to NTD!! the water conditions seem to be perfect! Every once in awhile I’ll see my betta, Alpha, chase one neon, but that’s barely ever, and he only does it for about 3 seconds, and is done for the week. He never catches them, that I’ve seen. They’re all comfortable together besides that, I’ll walk in and see alpha and one poking their heads out of a rock cave together. They don’t school 24/7, maybe because they’re school is so small, but they don’t seem stressed.

 

The school of Neons is pretty small. They maybe stressed and nipping at each other?
Bettas can be pretty sneaky as well, and may chase and nip the Neons.
The tumor could be an older wound?

You think its a tumor? D I have to remove it ? He chases them every once in awhile, for about 3 seconds before going back to minding his own business. It’s about once or twice a week he chases, besides that, I’ve seen neons literally right in front of his face, and he just ignores them. Actually, one of my neons loves him. Maybe because he has blue and red fins. he’s always following alpha. The neons chase each other, and swim together, and all do they’re own thing, which I guess mean they don’t feel the need to school for protection. I’m planning on upgrading to seven neon tetras, but my quarantine tank is about to be occupied, so after a couple weeks. (I’m getting a new betta who’s tank isn’t ready yet.)