Sexta poser…, originally uploaded by Fabiz Rabbit©.

Q: KG wrote,

I was wondering if you could help me again. I wrote a few months back. I had a betta who appeared to have Columnaris. You suggested that I use a combination of Maracyn and Maracyn II which worked really well on the first try. Unfortunately, my betta seems to have come down with the same disease. I have had him for a bit over a year. He lives in a 2.5 heated gallon container which stays at a steady 82 degrees. I do a full water change every 7 days and treat with Novaaqua and Amquel and add salt (1 teaspoon). I really don’t know what I am doing wrong. He was fine for some months and then something strange happened to the water. Much of the water had cotton like filaments. It seemed to have happened overnight. I quickly changed the water and changed the conditioner (thinking it was ammonia) but it was too late. He got fin rot and now that I seemed to have cured that the columnaris is spreading. I am worried that the bacteria is now immune to Maracyn/II or should I continue to use it? I bough Jungle Fungus Clear (not Jungle Fungus Eliminator?). I was told at the pet store that it might be effective if the Maracyn is no longer working but I was wondering if you could give me some advice whether I should continue to use the Maracyn combination. I have used it for 5 days. Should I do a 10 day treatment?If so do I change the water before doing the second treatment? I don’t want to torment the poor fish with chemicals. Thank you! I would really appreciate your help.

A: Flavobacterium Columnare or Cotton Wool Disease is a pretty common betta disease. One thing to make note of is we often call those fuzzy cotton patches Columnare or Columnaris (same thing) but truthfully, unless you have a microscope, we don’t REALLY know for certain which strain of bacteria it is. It could be something different from what your fish had last time. Since most hobbyists don’t have a microscope, we have to guess. So that said, I would recommend doing a second course of medication if it hasn’t gotten any worse. It’s not uncommon to have to do two courses. This is true for fish and human bacterial infections that require antibiotics. If the fuzzy patches were worsening as you treated with Maracyn-Two then you may want to consider a change to Jungle Fungus Clear or Eliminator. (same active ingredients though Eliminator has sodium chloride) The best step to avoid antibiotic resistant bacteria is to completely finish the full course of medication before switching to a new medication and always be careful to dose properly. If you’re halfway through a course of Maracyn-Two, finish that course before making a change. A full water change between switching medications is a good idea.

Also, Flavobacterium Columnare loves warm water and is very common in the spring and summer as our tanks heat up. Your fish may benefit by a slow decrease in water temperature. Try bringing it from 82F to about 76F slowly over the next few days.

As usual, keep testing your water regularly for stressors like ammonia, nitrite and nitrate that may leave your fish susceptible to these opportunistic diseases. Hope your Betta is back in action soon. Take care

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Reader Interactions


  1. Christie says:

    The yellow Betta in today’s photo is healthy and free of any signs of Cotton Wool Disease. If you have a clear photo of a Betta with this illness, email it in and I’ll post it for all to see. It’ll help countless Betta keepers identify illnesses in their own fish and of course you’ll get full credit for the photo. We’ll never resuse your photo without your approval.


  2. Anonymous says:

    Thank you Christie,
    I did just that, but unfortunately I think it was too much for him. The meds cleared away the bacteria but he still didn’t make it 🙁 . Unfortunately, I didn’t take any pics of the bacteria but it certainly wasn’t pretty – it pretty much just covered the poor fish in what looked like long strands of cotton. I think my major mistake was keeping the temp so high during the treatment because it encouraged the stuff to grow. Thank you so much for writing me back. I love your blog.

  3. Anonymous says:

    Very nice variety of clothes i ahve seen at Gap and Wilsons-Leather store through couponalbum site…

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