Acriflavine was used to treat sleeping sickness in WWI, and is being investigated as a potential potentiator of quinine drug action vs malaria(wikipedia, ). It may have synergistic actions with other anti-parasitics. I think it is a great thing that it manages to reduce the required dose of formaldehyde for anti-parasitic action so likely puts our fish under significantly less formaldehyde toxicity stress. This reduced toxicity in turn allows for safe frequent application of the bath. It is likely easier to maintain oxygen levels in a rally bath as well, again because there is less formaldehyde.The interesting thing is that Ruby Rally contains 'miniscule' amounts of formaldehyde. (Which surprised me). Perhaps acriflavine plays more of a role than formaldehyde.