Please someone correct me if I am wrong (i'm sure they will) but I have read the following about these product on more than one occasion, so if you do use it be careful and watch your parameters.
Treatments whitch use Malachite Green and Methylene Blue can be useful treatments for parasites and Fungus, unfortunately they can destroy our beneficial bacteria (I found this as an example here
Hope the melafix works for your fish
EDIT - sorry link does not work - but I have found another quote that might be helpful
They exert a mild anti-bacterial effect and in most circumstances will not destroy biological filtration bacteria, although they may ‘knock the filter back’ for a short while. However, it is still advisable to turn off or by-pass the filter system for a few hours if possible and as with any treatment always turn off any UV lamps. When using to treat against Ichthyophthirius (white spot or Ich) then it is important to keep the system running in order to destroy all stages of the parasite’s life cycle.
Again there are always different opinions out there - My policy is check it out thoroughly before your use it
I dosed with that and MelaFix/PimaFix yesterday then later, after reading that it was safe to do, I dosed again with the MelaFix/PimaFix.
All of the fish but one guppy female are more active today and appear to be doing better. I'm going to dose again with the MelaFix/PimaFix and hold off on the Ich Away because of what I have read in various places regarding Malachite Green.
What the fish have does not appear to be ich, it appears to be Fin and Tail Rot which Melafix/PimaFix treats. I will keep everyone updated.