Judging by the pictures in that article, it's quite possible that they have Epistylis.
A little extra information: I have 5 amazon puffers, 3 flag fish, 1 otocinclus, 1 butterfly loach and 1 ornate goby. Only the puffers have symptoms and the poor things swim around constantly brushing against things even rocks trying to get it off.
Environment: I have a 40 breeder with 2 medium co-op sponge filters and one Tidal 35 HoB. And after reading that article, I think it's reasonable to say that I feed too much.
I will try to acquire Kanaplex or Maracyn 2 today. I will continue Ich-X in the meantime but instead of doing 50% water changes, I will increase that to 95% and thoroughly clean the tank.
Should I consider picking up a 10 gallon and treat the puffers in that, or are they better off remaining in the 40B?
Thanks for your help.