'Malachite green, also calle aniline green, basic green 4', diamond green B, or victoria green B, IUPAC name:4-[(4-dimethylaminophenyl)-phenyl-methyl]-N,N-dimethyl-aniline is a toxic chemical primarily used as a dye. When diluted, it can be used as a topical antiseptic or to treat parasites, fungal infections, and bacterial infections in fish and fish eggs. It is also used as a bacteriological stain.