Uses
Malachite green is traditionally used as a dye. Millions of kilograms of MG and related triarylmethane dyes are produced annually for this purpose.
MG is active against the oomycete Saprolegnia, which infects fish eggs in commercial aquaculture, and other fungi. Furthermore, MG is also used as a parasiticide and antibacterial. It is a very popular treatment against ichthyophthirius in freshwater aquaria. The principal metabolite, LMG, is found in fish treated with malachite green, and this finding is the basis of controversy and government regulation. See also Antimicrobials in aquaculture.
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