Suggestions range from copper, malachite green and other remedies, with some recommended being used in conjunction with formaldehyde. However the general consensus is these types of medications are either largely ineffective or do not work at all, and that the best and most effective treatment for Brooklynella is formaldehyde alone. Typically a standard 37% formalin solution is mixed with either fresh or saltwater in a separate treatment container, intitially all fish are given a quick dip or a prolonged bath, followed by continued treatment and care in a QT. Of course the longer fish are exposed to the formalin treatment, the more effective it will be at eliminating this "disease". Whether to administer a dip or a bath to start with is something you will have to determine yourself, but there's a very simple way to do this.