If you want to have tour tank stained blue, use the M. B. If you want to use M. B. for hatching tanks, ay least for corys you need to remove the blue when you see wigglers. A longtime breeder of corys taught me that the M. B. could damage their gills as they are forming.
One thing M. B. can do is to help remove nitrite from fish and help them get the oxygen they need. But M. B. was initially used to stain things on slides.
It works in fish too.
Here is what Fritz (who now makes Maracyn Oxy) says about it;s uses n aquariums:
I have a small bottle of M.B. I don't often use and a big bottle of Maracyn Oxy which I do use more often.
Finally, because M. B. stains the water, it makes it difficult or impossible to use most of our test kits beause they mostly rely on the color of the tested sample to reveal the results.
Here is a paragraph from a study of columnaris in rainbow trout. I know this is a colder water fish not usually kept in tanks, but the disease affects all kinds of fish from those in arctic waters to those in warm tropical waters.
(bold below added by me)
from:
Heidi M.T. Kunttu, E.Tellervo Valtonen, Lotta-Riina Suomalainen, Jouni Vielma, Ilmari E. Jokinen,
The efficacy of two immunostimulants against Flavobacterium columnare infection in juvenile rainbow trout (Oncorhynchus mykiss),
Fish & Shellfish Immunology,
Volume 26, Issue 6, 2009, Pages 850-857,
ISSN 1050-4648,
https://www.sciencedirect.com/science/article/abs/pii/S1050464809000977
or
Mainous, M.E., Kuhn, D.D. and Smith, S.A., 2012. Efficacy of common aquaculture compounds for disinfection of Flavobacterium columnare and F. psychrophilum.
Journal of Applied Aquaculture,
24(3), pp.262-270.
Abstract
Flavobacterium columnare and
F. psychrophilum are important pathogens of the aquaculture industry, and thus disinfection of aquaculture systems and equipment is essential for disease control. This study examined commercially available compounds
in vitro for their ability to eliminate these two species of
Flavobacterium from the water. The compounds evaluated included Clorox, ethanol, Roccal, Lysol, iodine, formalin, Chloramine-T, glutaraldehyde, potassium permanganate, sodium chloride, and Virkon Aquatic. In this study, 70% ethanol, 50% ethanol, Clorox, Roccal, Lysol, iodine, glutaraldehyde, Chloramine-T, and Virkon Aquatic reduced the number of bacteria of both species to zero within one minute of contact time. Formalin and 30% ethanol also killed both species of bacteria, but required a longer contact time. Potassium permanganate killed
F. columnare within one minute, but did not reduce the numbers of
F. psychrophilum even after one hour of contact time.
Sodium chloride was not effective.
(Bold added by me) from
https://www.tandfonline.com/doi/abs/10.1080/10454438.2012.708291
Columnaris ranks very high in the list of diseases found in farmed food or ornamental fish as well as fish kept in home Aquariums. As a result, there is a fair amount of research into this disease and a lot more is known today than even 10 years ago. When I do a Google Scholar search for Flavobacterium Columnare I get back "About 8,840 results (
0.10 sec)" if I modify that by adding the word symptoms, treatments, virulence etc. I get even more.
The most common use of aquaculture is food fish for human consumption. This indutry is highly regulated as tio the permittable drugs that can be used. We do not have such limitations in our tanks. So we have an advantage, especially here in the states. We can buy and use a very broad choice of medications which are not available to the food fish farmers.
Columnaris is also the disease/infection I have most had to deal with over the years. I have always treated it with antibiotics and I have a decent cure rate but not a perfect one. I also remember a bunch of years back reading about using Chloramine T. I found this:
Ilhan Altinok,
Toxicity and therapeutic effects of chloramine-T for treating Flavobacterium columnare infection of goldfish,
Aquaculture,
Volume 239, Issues 1–4,
2004,
Pages 47-56,
ISSN 0044-8486,
(
https://www.sciencedirect.com/science/article/pii/S0044848604002984)
This was published in 2004 and boy was i surprised to learn a thing most of us work to keep out of tanks was a potential cure for columnaris, or at least a way to kill the "bug."