Methylene Blue for Treating Fish / Crayfish / Crawfish

Methylene blue (CI 52015) is a heterocyclic aromatic chemical compound with the molecular formula C16H18N3SCl. It has many uses in a range of different fields, such as biology and chemistry. At room temperature it appears as a solid, odorless, dark green powder, that yields a blue solution when dissolved in water. The hydrated form has 3 molecules of water per molecule of methylene blue.Methylene blue should not be confused with
methyl blue, another histology stain, new methylene blue, nor with the methyl violets often used as pH indicators.

The International Nonproprietary Name (INN) of methylene blue is methylthioninium chloride.


Methylene blue popular used in aquaculture and by tropical fish hobbyists as a treatment for fungal infections. It can also be effective in treating fish or crayfish/crawfish infected with ich, the parasitic protozoa Ichthyophthirius multifiliis. It is usually used to protect newly laid fish eggs or crayfish/crawfish egg from being infected by fungus or bacteria. This is useful when the hobbyist wants to artificially hatch the fish eggs. Methylene Blue is also very effective when used as part of a "medicated fish bath" for treatment of ammonia, nitrite, and cyanide poisoning as well as for topical and internal treatment of injured or sick fish as a "first response"
\for treating fish / crayfish / crawfish infected with ich or fungus should only be less than 10 minutes