try 30+% formaldehyde (formalin), since brooklynella is not affected by copper. (btw, malachite is copper)
but as much as possible, don't use malachite and formalin for dips, especially if the fish is newly purchased. QT with meth blue first (for a few days, kung matyaga ka, weeks.), then if even a slight possibility of brooklynella appears, do a FW+formalin dip.
hth