Wear gloves and goggles when handling malachite green or formalin. Do not inhale the fumes of formalin and always handle in a well-ventilated area. Both are potentially dangerous. Malachite is a respiratory poison as well as being a suspected carcinogen.
Malachite green penetrates deeply into fish body tissues and may have a use against Proliferative Kidney Disease (PKD) in salmonids.
It is likely that malachite green will be banned in the near future
Malachite green is de-activated by light
Malachite green is reported to be toxic to tetras, catfish and loaches and small marine fish
Formalin should be stored in the dark and above 40C to prevent the formation of paraformaldehyde
Formalin is extremely irritation to gills and should not be used where there may be existing gill damage or where skin ulcers are present.