http://www.petsforum.com/personal/tr...oklynella.html
Try this method and qt the fish for 4 weeks before putting them back in the main tank. I would treat the QT tank with formalin to get rid of the parasite from there as well. If you get more in the main tank you'll have to move them all to the QT and leave the display empty for 30 - 40 days so It can't complete its life cycle. (it needs a fish to host similar to ich) It seems water conditions play a big role also make sure your water is perfect. I'm no expert but I just went through this as well and did alot of research.