|This is a copy of an email I received from Scott Hieber It
has to do with a discussion of Malachite Green used as a treatment for
diseases in aquariums. The "old" school believed that it contained Copper,
while in fact it did not. Here is his email, it explains it very well
and I think all will find it interesting.
Copper is sometimes used for treating aquaria parasites because it's toxic at pretty low levels to parasites (and Plants)! At higher levels it severely stresses fish and at yet higher doses, its lethal. Mardel makes Copper products for killing ick -- one is called Coppersafe but I think that is an oxymoron. I don't know anyone else that makes it for that purpose but there might be some out there. From what I have seen, copper has fallen into disuse as anti-parasitic because Malachite Green and formalin are very effective at nontoxic levels to plants and less stressful levels to fish.
Twenty-five years ago (as today) Copper was sold to treat ick, but back then people were also still selling Methylene Blue under the mistaken belief that it had antibiotic or anti-parasitic properties rather than merely retarding some bacterial growth. The aniline dye known as Malachite Green (also known as benzaldehyde Green) is a particular chemical that is made up of carbon, hydrogen, nitrogen, and chlorine atoms. I don't think a manufacturer could have legally labeled a product as "Malachite Green" without labeling the container as containing Malachite Green (a particular chemical) AND Copper if it contained Copper. . .But who knows. . .Twenty-five years ago the vendors told us we needed air pumps and air stones to keep the water oxygenated.
Formalin (solution of CH2O, formaldehyde, in water) is also used
as fish medicine in place of or mixed with Malachite Green. For example,
Quick Cure is such a mixture. Although formalin is extremely effective,
it is reportedly more toxic than Malachite Green. It's extremely toxic
at high concentrations. It's the chief constituent of embalming fluid.
Here's some web facts on malachite green (the dye, not the mineral)