Malachite green is bad stuff... causes liver cancer in humans. Check out this site... it also says it's toxic to fungus, and algae.
hyposalinity is a MUCH more effective and less stressful treatment for cryptocaryon (sp?) than copper. i always use hyposalinity before introducing a fish into my reef tank.From the article:
So... is the use of Malachite Green "worth it"... That is, worth the risk of poisoning your livestock... A qualified "yes", particularly for freshwater and pond use... for fungused eggs for production facilities of these fishes, common ich and velvet problems... But not warranted IMO in marine applications... Just too dangerous IMO, easy to make mistakes with with seawater use. Better to stick with tried and true copper formulations that can be tested for, and have a bit wider efficacy.