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Sunfish mouth rot; Cotton Mouth; Columnaris

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#1 DissidentMantis

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  • Illinois

Posted 26 November 2019 - 03:56 PM

I have noticed that some of my fish have developed (cottonmouth) or (mouth Rot).  It looks like white fuzzy mucous that builds up around the inside of their mouths, and I have noticed one of my Pumpkin-seeds actively spitting it out.  I do frequent water changes and I have ample filtration so I am not sure how they got the mouth rot.


The cottonmouth comes and goes, one week a fish will be exhibiting symptoms, and the next week it will be completely gone.  


One possible cause is from their diet.  I feed them a mix of flatheads, danios, guppies, mealworms, waxworms, and night crawlers on a daily basis.  Some of he guppies have looked like they were in poor shape, and I haven't quarantined any of my feeders because my LFS claims that they do that for me.


How do I go about treating this issue? Can I treat it in my tank? I have a heavily planted tank with fixed structure, so removing the fish to transport them to a quarantine tank would be bordering on impossible.


I have attached some photos below but it is really hard to see in the pictures.  I also added a photo of my tank so that you get an Idea of why i will not be able to remove the fish, (they have tons of heavy rocks and driftwood to hide under) and I do not want to take apart my arrangement.



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Edited by DissidentMantis, 26 November 2019 - 03:58 PM.

#2 gerald

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  • Wake Forest, North Carolina

Posted 26 November 2019 - 05:56 PM

Could it be from mouth-to-mouth fighting?

Gerald Pottern
Hangin' on the Neuse
"Taxonomy is the diaper used to organize the mess of evolution into discrete packages" - M.Sandel

#3 littlen

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  • Washington, D.C.

Posted 27 November 2019 - 07:26 AM

Supposing that it is an infection, without proper medication/treatment it will never fully go away even with the best filtration and water change schedule.  I'll subscribe to Gerald's idea that it could be minor flesh wounds from fighting.  Especially since you say it comes and goes. 


I'm leery of the guppies being truly quarantined at your LFS.  They aren't valuable enough to be put through a proper [medicated] quarantine.  My guess is they let them sit in a tank for a week, maybe 2 before selling them.  Thinking that they must not have any infectious agents in/on them since they are still alive.  Live foods are good, and I like what you offer your fish.  But there is no reason not to be able to put them on a pellet diet with the occasional life food offering as a treat.

Good looking tank BTW.

Nick L.

#4 DissidentMantis

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  • Illinois

Posted 02 December 2019 - 12:27 PM

thank you for the responses.  I did catch these fish on hook and line and the tank is only a month old.  I suspect the infection could have started with the initial mouth wound from the hook.  This could have been exasperated from mouth to mouth fighting (which they do engage in).  I removed one sunfish to reduce over crowding, he was also the trouble maker of the tank. He is now in a quarantine/breeder tank.  I treated the tank with API General cure, then API Fungus Cure over the holidays and it seems to have worked.  The Fungus cure turned my tank green and required fresh activated carbon and a 50 percent water change to return to normal. 


Native fish keeping has certainly kept me busy, between picking off anchor worms with tweezers, to treating mouth rot and trying to switch these guys to a pellet diet, I am certainly getting a run for my money.

#5 littlen

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  • Washington, D.C.

Posted 02 December 2019 - 01:48 PM

If it is any consolation, you're doing it the right way.  Good on you for the attention, care, and determination you're putting towards your tank.

Nick L.

#6 gzeiger

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Posted 02 December 2019 - 03:34 PM

The good news is that pellet training sunfish is easy. Sort of. Sunfish are quick learners. Once one of them recognizes a pellet as food, the rest will compete for them enthusiastically. But they won't touch a pellet when live food is available. It's perfectly fine to let them go a few days without food to get started.


In the long run pellets will be healthier than feeders from a pet store. You're virtually guaranteed a run of ich or other disease doing that for an extended period. I'm not sure what your local laws are like. In SC I used to get a bucket of mosquito fish and crawdads every so often and dump them in a tank. I had one fish that would eat until his sides were visibly bulging, swallow one more so his gills wouldn't shut all the way, then catch just one more and hold its tail between his lips, swimming around like that until he digested enough to swallow it.

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