Sterbai with columnaris. Need help please.

[42nokomis]

I have a Corydoras sterbai with a lingering slow growing columnaris. My question is: How much salt can a C. sterbai tolerate? I did a course of 13 days with Furan-2 and Kanaplex. Lesions faded but remain. I am treating her with methylene blue + salt baths twice daily now. After 5 days of baths the lesions faded but still remian. There are three other C. sterbai, one White cloud minnow and one fancy guppy in my 20 gallon long with no symptoms at all. All live plants died from the antibiotics so now I have only silk plants and little rock caves. Can you point me to a forum that addresses treatment of columnaris in corycats? I spent quite a bit of time already looking.

Thank you very much.

Sandra

[TwoTankAmin]

I tend to search the scientific literature for this sort of information. I can find many papers dealing with columnaris, but not one that specifically looked at corys let alone sterbai. Most of the research on treatments for fish concentrate on food fish. This is because the medication must be found to be safe for human consumption of it cannot be used. This means our ornamentals are often ignored by researchers.

One of the most effective treatments is an herbicide called Diquat. This is not the sort of thing the average keeper may not want to use as it can be dangerous. It was discovered to be effective on columnaris by accicdent in 1972 as far as I can tell, it is an aquatic weed killer. It was sued in fish ponds where there were fish with columnaris. After the diquat was used, the columnaris was gone. It is particularly useful with the most virulent strains.

Thomas‐Jinu, S. and Goodwin, A.E. (2004), Acute columnaris infection in channel catfish, Ictalurus punctatus (Rafinesque): efficacy of practical treatments for warmwater aquaculture ponds. Journal of Fish Diseases, 27: 23-28. https://doi.org/10.1046/j.1365-2761.2003.00504.x

Abstract

Columnaris disease was induced in channel catfish, Ictalurus punctatus (Rafinesque), by bath exposure to four highly virulent isolates of Flavobacterium columnare. In untreated controls, mortality began 20 h after exposure and reached 100% by 48 h. Mortality in channel catfish given antibiotic treatments with oxytetracycline or a combination of sulphadimethoxine and ormetoprim in feed prior to bacterial challenge was zero with all four strains of F. columnare. Diquat® (Zeneca Agricultural Products, Wilmington, DE, USA) was the most effective bath treatment; mortality with all four strains was zero. With potassium permanganate, chloramine‐T, hydrogen peroxide and copper sulphate, bath treatment efficacy varied significantly among strains (P = 0.0346) and among treatments (P = 0.0033). Bath treatments with chloramine‐T and potassium permanganate significantly reduced (P < 0.05) mortality from 100 to 75 and 69%, respectively, but copper sulphate and hydrogen peroxide treatments were not effective. Based on our results, oral antibiotics prevented columnaris disease but, of the bath treatments, only Diquat® produced a dramatic reduction in the mortality of acutely infected fish. Diquat® is labelled for aquatic use as an herbicide in the USA but in large ponds it is prohibitively expensive.


I have never tried this treatment. I have always had goof luck with Mardel Marycin. However, there are a lot of strains of F. columnare some of which have become resistent to some antibiotics. Without testing for what strain you have, it is hard to know what wont work re antibiotics.

Here is another interesting paper. There are virus that will attack bacteria. One called FCP1 phage has been tested for use against columnaris and was proven pretty effective. I have no clue where one could get ahold of FCP1 phage.

Prasad Y, Arpana, Kumar D, Sharma AK. Lytic bacteriophages specific to Flavobacterium columnare rescue catfish, Clarias batrachus (Linn.) from columnaris disease. Journal of Environmental Biology. 2011 Mar;32(2):161-168.
https://europepmc.org/article/med/21882649

Abstract
This investigation was aimed to find out appropriate strategy against antibiotic resistant bacterial fish pathogen, F. columnare. This pathogen was found persistently associated with fishes causing columnaris disease and ensuing mass mortality in hatchery and culture system of Sub - Himalayan region. Nine lytic F. columnare phages (FCP1 - FCP9) specific to its fifteen isolates were isolated from the water and bottom sediments of various geo-climatic regions of North India. The F. columnare phage FCP1 (made of hexagonal head and non contractile long tail belonging to family Podovariedae, a member of DNA virus) exhibited broader host range to lyse 9 out of 15 isolates of F. columnare. Therapeutic ability of FCP1 phage was assessed in C. batrachus inoculated intramuscularly (im) with virulent bacterial isolate FC8 and post inoculated (PI) with FCP1 phage (@ 10(8) : 10(6):: cfu : pfu) through intramuscular (im), immersion (bath) and oral (phage impregnated feed) treatment. Significant (p < 0.001) reduction (less than 10(-3) cfu ml(-1)) in host bacterium in the sera, gill, liver and kidney of challenged fishes was noted after 6 hr of phage treatment. Quantum of phage played a significant role in bringing down bacterial population as in the sera of dose 1 (@ 4.55 x 10(6) pfu ml(-1)) and dose 2 (@ 9.15 x 10(6) pfu ml(-1)) treated fishes mean log10 cfu value reduced by 3 logs (58.39%) and 5 logs (73.77%) at 96 hr, respectively. Phage treatment led to disappearance of gross symptoms, negative bacteriological test, detectable phage and 100% survival in experimentally infected C. batrachus. Result of this study provides evidence of profound lytic impact of FCP1 phage and represents its interesting therapeutic importance against antibiotic resistant F. columnare.

Here is another study which looked at a different phage which was very effective.

Laanto E, Bamford JK, Ravantti JJ, Sundberg LR. The use of phage FCL-2 as an alternative to chemotherapy against columnaris disease in aquaculture. Front Microbiol. 2015;6:829. Published 2015 Aug 19. doi:10.3389/fmicb.2015.00829
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4541368/

I am not sure if any of this will help. But if you are curious enough and have some basic science understanding,
https://scholar.google.com/scholar?q=F. ... s_yhi=2021

[42nokomis]

Thank you TwoTankAmin for your help with this. I also found that 95% of information in articles about columnaris dealt with commercial fish. I have, since this initial inquiry, been using methylene blue+salt baths with modest success. The lesions remained. Yesterday I was able to acquire some Merbromin which I have applied witha q-tip to the lesion directly. It worked!! In 24 hours the lesion was 50% better!! I am continuing this along with the above mentioned baths. Thank you so much for the papers you cited.