Good to hear that your fish are doing well!! youve done the right thing by separating out the smaller fish and the bigger fish. Just a quick note though, is the "special stuff" malachite green? If it is, just be careful. Malachite green is a mutagen and a carcinogen, whilst you'd need to drink the stuff to really hurt you, its worth at least knowing what your exposing yourself to, the most dangerous part of it is the dried flakey stuff around the top of the bottle. If you've got Cichlids and platties with no plants your probably best just to use a weak salt solution, about 5ppt (5 grams of salt per litre) of course salt without iodine and anti caking agents should do the trick, works wonders on skin infections as it kills the infective agent and helps the fish maintain osmotic balances (freshwater fish are "saltier" than the surrounding water so they "leak" there salts out if they have skin infections) no good for soft water species like tetra's and anything else from the amazon though.