Neon tetra with white stuff on fins


Ammonia - 0
Nitrite - 0
Nitrate - 20

I have this neon tetra for 7 months now and he has always had that tumor on his face so I’m not worried about that,.. but my issue is with his fins.

His fins seem to look white at some parts. I thought it was fin nipping because a few other tetras have them too. However, I now noticed that his body has two white spots as well and it doesn’t look raised or rotten to me. I just recently put one of the tetras in a breeding tank alone to see if the white spots where due to one of the fishes nipping at him.

What else could it be?



The fish looks to be in poor condition.

I think that all of the white marks are Columnaris.

The bacterium lives on the fish but is able to attack the living tissues when the immune system does not defend the fish adequately.

A suppressed immune system could be due to a variety of stress - causing reasons.

Treatment involves identifying these causes and improving the situation.

Water quality including ammonia/nitrate/oxygenation/temperature/pH/hardness should be looked at.

Stress from other tank-mates could be an issue as could how secure the fish feel. Plant cover and a good size shoal of their own kind may be important.

I would suggest it may be futile to use medications if the causes of the problem are not addressed.
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From what I've read around if your fish is alive for more than 2\3 days with those marks it may not be columnaris.

If you have a problem with bacteria in the water tank it may not solve it, but maybe try to rise the temperature of the aquarium for a few days if the rest of your stock allows it, to 29\30 degrees centigrade (make sure the tank is well oxygenated, the higher the temperature, the easier the O2 escapes). That is how I've successfully treated white spot in the past. What your fish has is not white spot, but not based on theory but experience, neons get ill easily in water with lower temperature. Also make sure that with water changes you never add water with the same temperature, neons suffer a lot because of changes in water temperature. Years ago I killed all my neons with a water change in winter...
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Hey guys.

I bought 5 neon tetras at the same time, 2 weeks later or so... 3 of them displayed white areas on their fins and 2 of them had the bulging tumor things on their mouths. The jagged fins come and go which I assumed may be due to fin nipping.

I don’t think it is columnaris though because they have had this issue for the past 7 months now; they should have been dead already.

I think oxygen levels are fine because I don’t see any of them gulping at the surface and no tank mates are swimming erratically.

Tankmates are:
1 Veiltail Angelfish-never aggressive/territorial
1 Betta Male - never aggressive
4 Guppy Female
1 Bristlenose Pleco Baby
2 Siamese algae eater
2 Oto

I’ll keep you guys updated on his status in the isolation tank.
Thanks guys!
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Its a good sign that you have kept them alive for such a long time. It may be possible to cure them completely.

I've bought Neon Tetras which displayed similar Columnaris symptoms for 18 months after purchase before the symptoms eventually disappeared. Some of my fish were lost soon after purchase, however.

There are many strains of Columnaris that vary in virulence and many situations where the Columnaris may develop fast or slow.

Given that Columnaris is known to be the main disease of Neons that shows these symptoms I would expect it to be that. Neon Tetra Disease is rare in Neon Tetra as shown by a an expensive scientific investigation in France. The Bubble-mouth disease is something else but I have seen it disappear on my Neons without causing any deaths.
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