As was pointed out, neither Meth Blue nor Mal Green is going to cure this in any dose. In the case of parasites, the best first step is always a dip in full strength seawater. I would do the seawater dip and then transfer the fishes to a new "sterile" tank. Break down and drain the old tank and let it go dry (filters too) for a couple of weeks. Very few fish parasites can live two weeks outside of water and the key to getting rid of parasites forever is breaking their life cycle. If the salt dip does not work, the next step is a formalyne dip.
Parasites are usually best treated through a short term dip rather than medicating an entire aquarium. This is because the concentration of medicine needed to actually kill the parasites is usually harmful with prolonged exposure. The key will be treating the fishes and moving them to a "clean" environment after each treatment to break the parasite's life cycle.
"My journey is at an end and the tale is told. The reader who has followed so faithfully and so far, they have the right to ask, what do I bring back? It can be summed up in three words. Concentrate upon Uganda."
Winston Churchill, My African Journey