MB is often used to prevent fungus on egga by many tropical fish breeders in this and has been recommended in the literature for over a century, interestingly there is no much evidence at acgtually works!

Mag, that's why my right on: The efficacy and tolerability of methylene blue cannot be generalized and vary from fish species to fish species. In the worst case, the wrong or inaccurate dosage is even causing damage. In addition, mb is not completely safe for humans. There are super alternatives against spawning fungi that make the use of mb obsolete: water change, salt or leaves / Alder Cones *. If you - for whatever reason - don't get around the use of mb, the treatment should always be so short Being held as possible.

* with reservation - more detailed research will follow!

, here comes the " ": At Park et al. (2019) Methylene Blue LED to a lower survival rate of eggs - but the concentration was also much higher than we would normally use. So let's take a look at studies where the concentration of use is closer to the recommended 2 MG / L:

Chambel et al. (2014) have eggs from Zebra (⛱. Rerio), mourning coat salmler (. ) and Scalar (🐙. Scalare) incubated with concentrations of 0.5 to 3 MG / l. I leave the scalars out because the hatching rate of the control group is almost 0 and therefore the results are not meaningful. For the rest of the two species, the study comes to completely different results! While there was a clear improvement in the hatching rate in the mourning coat 3 MG / l, there is no difference in zebra bling to the control group without mb.

Yeasmin et al. (2016) made a similar attempt with carp (⛱. Carpio) and mb concentrations of 1-5 mg / l. Improvement in the hatching rate at 1 AND 3 MG / l and a deterioration at 5 MG / l were seen. A reference is attached to an image: the first three cuvettes show 2, 3 AND 5 MG / l. Therefore, I also see the dilution "according to eye measure" - at least don't trust me to distinguish the 3 and the 5 MG / l according to colour intensity - which (in carp) already makes the difference between success and failure!

In all the books on fish medicine I know, methylene blue, if any, is only briefly addressed - mostly as a means for nitrite poisoning. Khoo (2000) even writes explicitly that there is not enough evidence that using mb against spawning fungi would help.

There are a lot of good alternatives. Especially for medaka breeders will be interesting that yeasmin et al. (2016) have been able to observe that nacl works as good as mb. 1 G / l nacl resulted in a similar level of hatching to 1 MG / l mb and the inhibition of bacterial growth was similar. (of course, salt must also be weighed whether a fish species can handle it).

So there are rather few reasons for using mb. On the contrary, studies prove that in addition to acute and long-term toxicity, fish also teratogenic effects (faulty development) occur. This was how scalar problems with the swim bubble and American Stubble (Promelas) were worse growth.

As a photosensitizer, mb attacks the cells in conjunction with light. This also means that all values can only be enjoyed with great caution, because light makes mb a lot more aggressive. In addition, mb is classified as irritating and corrosive according to ghs, so it can also be harmful to humans.

Chambel, J., Costa, R., Gomes, M., Mendes, S., Baptista, T., & Pedrosa, R. (2014). Hydrogen peroxide, iodine solution and methylene solution highly enhance the hatching rate of freshwater ornamental fish species. Aquaculture International, 22(6), 1743–1751. doi: 10.1007/s10499-014-9779-1

Khoo, L. (2000). Fungal diseases in fish. Seminars in Avian and Exotic Pet Medicine, 9(2), 102–111. doi: 10.1053/ax.2000.4623

Kinoshita, M., Murata, K., Naruse, K., & Tanaka, M. (2009). Medaka: Biology, Management, and Experimental Protocols. John Wiley & Sons.

Methylene blue. (n.d.). Retrieved from https://pubchem.ncbi.nlm.nih.gov/compound/Methylene-blue on 23.11.2019.

Noga, E. J. (2010). Fish Disease: Diagnosis and Treatment. Somerset: Wiley.

Park, I.-S., Baek, S.-W., & Moon, K. H. (2019). The Sterilization Effect of Methylene Blue, Formalin, and Iodine on Egg and Adult Stage of Marine Medaka, Oryzias dancena. Development & Reproduction, 23(3), 199–211. doi: 10.12717/dr.2019.23.3.199

Rifici, L. M., Cherry, D. S., Farris, J. L., & Cairns, J. (1996). Acute and subchronic toxicity of methylene blue to larval fathead minnows (Pimephales promelas): Implications for aquatic toxicity testing. Environmental Toxicology and Chemistry, 15(8), 1304–1308. doi: 10.1002/etc.5620150807

Tuite, E. M., & Kelly, J. M. (1993). New trends in photobiology. Journal of Photochemistry and Photobiology B: Biology, 21(2-3), 103–124. doi: 10.1016/1011-1344(93)80173-7

Yeasmin, S. M., Rahman, M. A., Hossain, M. M. M., Rahman, M. H., & Asif, A. A. (2016). Identification of causative agent for fungal infection and effect of disinfectants on hatching and survival rate of common carp (C. carpio) larvae. Asian Journal of Medical and Biological Research, 1(3), 578–588. doi: 10.3329/ajmbr.v1i3.26481

-----------

Taken from "Meg's Medaka Page" on Facebook, Nov. 2019.