Can Columnaris Become "active" With No External Trigger / Reason?

  • #1
HI all,

(I know it's not nice posting something like this without picture, but I'm at work now and I doubt I'll be able to take a good pic anyways, but I'll try later today at home)

I have a separate 10g tank for 5 platies that survived my huge disease outbreak in 65g in December and it has been more or less fine for a few months now. I started noticing an issue with one of the male platies recently - I initially saw him hiding somewhere all the time and showing up only during feeding time for a week or so and yesterday I noticed his tail was damaged (but it didn't look like fin rot and damaged edges, more like a razor-accurate cut parallel to the spine - I figured he might've run into some sharp decor). But most importantly - there is some small white thing on his mouth. It is small enough to not see if it is fluffy or not (most likely not), but bigger than ick spots.

Bad thing is that there is a gender imbalance in the tank - we initially thought those were 5 male platies (my wife bought them back when we literally knew nothing about tanks), however those are 2 females and 3 males and this male has been bullied and picked by 2 other males from time to time.

I haven't done anything drastic yet, just dropped some melafix yesterday to help with tail healing (I know it won't do anything if it is really columnaris...), but started researching things today and a little lost. Most sources say that "mouth rot"-like symptoms are a sign of columnaris which is normally very lethal and contagious and can kill in days. This guy seems to be behaving like this for almost a week and probably had this thing on his mouth for at least the same period. Plus I haven't introduced any new fish, plants or decorations since I started this tank fresh back in January - these 5 platies have been the only inhabitants of this tank ever.

That said, do you think it can really be columnaris or what else can have such a symptom (some white-ish thing on a lip)? Can this be triggered just by tankmate bullies and show up literally from nowhere?

I don't want to pull the trigger immediately and start Kanaplex/Furan in this tank unless I am 100% sure it is bacterial. Can it be just some kind of a damage e.g. from the fight?

Water params: 74-75F, API drop test readings from yesterday are 0/0/5, my last water change was 3-4 days ago and I aI'm to change around 30-50 % once a week now (or when reading shows visibly more than 20 nitrates...)



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  • #2
Yes columnaris can seem to show up out of no where. In reality the bacteria is always present in the water and infects in an opportunistic manner. However, even the slowest of columnaris infections will kill fish within a week or two. It is also possible that you have a fungal infection because these can present very similarly to columnaris.
  • #3
I read it's always 'there', but needs a weakened fish to take hold, then multiple, then spread to others.
  • #4
Fish do not get fungal "infections"
This is just not true, fungus dosent "infect" any fish. It eats dead tissue. Just like fungus dosent kill people or trees or animals, but it does break down already dead or diseased tissue.
The underlying cause is always bacteria. Please don't go around telling people their fish have fungal "infections"
  • #5
Kanamycin is a poor antibiotic. Furan is dixion, and they put dixion in pesticides, including defoliant agent orange. Please do not use furan!
There are much better choices out there for antibiotics, such as tetracycline antibiotics, or sulfas.
  • #6
I don't mean to start a fight, but fungal infections can destroy healthy skin in both fish and humans (eg. athlete's foot, ringworm, mucormycosis- a flesh eating fungus). Also what's your temp, OP, as a lower temp can cause columnaris to move slower, if that's what it is.
Sorry, just saw temp, that's actually a good temp to slow columnaris
  • #7
I thought furan 2 was the go-to cure for columnaris? A gram-negative bacteria.
  • #8
I've heard of furan-2 working well along with kanaplex being a great cure... I don't know though, haven't tried personally...
  • #9
I recently used that combo and seems fine. Lost 2 Cory's in 12 hours, but didn't lose any more fish once started that evening. Put me into a minI cycle that I'm still working through.
  • #10
There are other antibiotics that work just fine for bacterial infections. Just because its a bacterial infection, dosent mean its always columnaris.
Any fish with a bacterial infection bad enough to look sick with rotting fins, has a slI'm chance of making it, despite the type of bacteria.
Its really a "prevent it if you can" type thing, not a "use this and its always gonna work" Type thing as you make it seem.
Oxytetracycline, Doxycycline, SMZ-TMP, triple sulfa, minocycline, all will work for these type of end-stage,bacteria infections. At least, work better than doing nothing.
  • #11
I have used kanamycin furan 2 combo on fish who had a pretty visible bacterial infection. I didn’t lose any so I wouldn’t completely rule those two out. Triple sulfa I have heard is great for early bacterial infections but IF it is indeed columnaris these meds don’t work as well if the infection is not early stage.

White wolf you are right that there must be an underlying vulnerability for a fish to present with fungus- but they most definitely can be affected by a fungus.

Some pics of the fish could really help diagnose
  • Thread Starter
  • #12
Thanks a lot to everyone for advice!

I am not jumping into any antibiotic treatment right away - ideally I want to get away with as little meds possible starting with things like Paraguard and - only if absolutely necessary - switch to something stronger.
I tried taking some pics today before the water change and some good news that this "lesion" on his lower lip actually became much smaller than it was yesterday. I still very much hope it is NOT columnaris, but I guess over the next few days we'll see for sure. He is quite a fast guy, so it was extremely hard to snap a good still picture, so apologies for a very bad quality. I put some markings in red over what I was concerned about...


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  • #13
I agree with you about holding off with treatment. It is hard to tell based off of those pictures, but I’ll keep my fingers crossed for you!
  • Thread Starter
  • #14
I tried snapping more picture with the camera, but I can't seem to focus properly on this guy when he's facing me. Hope these pictures can tell something... (as you can see, this whitish thingy is really small)


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  • #15
I wanna say I have something similar right now, but can't really find what it actually is on my barb. It's been there for maybe a month or so on his tail. I also can't find any info on it, the fish are all acting fine, schooling, eating. Let me know what you think of this. The top barb has that dot on his tail, which clearly isn't ich.


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  • #16
Take a look at saprolegnia.

It looks like columnaris but can be treated with malachite green based meds such as ParaGuard.

Do you happen to have any fuzz covered food in the tank?
  • #17
Paraguard will keep it from spreading, but not treat it. IF that's what is really is.
Columnaris and paraguard - Seachem Support Forums
I just treated it in my tank with furan 2 and kanapax, and it killed my cycle.
  • #18
Ill say it again and again and twenty years from now people will still think their fish are getting "fungus" infections.
It is bacteria, and the "fungus" (actually water mould) only eats DEAD TISSUE.
Fungus does not simply live on live skin, in nature fish swim around all kinds of dead decaying matter, dead birds, logs, trees falling into the river or lake decomposing, mushrooms growin on the dead logs, it simply is a part of nature, and NO it does not become "pathogenitic" as in fungus spreading and growing and killing fish no no no
Bacteria, namely F. Columnaris, is always present in water, and does this. Your fish have bacterial infection and need an antibiotic. You may not believe me now, but in time you will see. If you kill the bacteria, the fungus falls off by itself. Dont even have to treat for it. BUT if you dose with a anti-fungal such as paraguard or M blue, the fish will stay sick. The fungus may fall off but then regrow as soon as you take it out of the medicated water, the reason, the skin is being consumed by bacteria. Need to give fish antiboitc.

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