Levamisole is an often recommended medication for treating parasites, especially camallanus worm. Unfortunately this medication must be dosed low enough to keep the fish safe and it does not always kill the parasites. More often than not it will only paralyze the parasite. This is why it is critical to dose carefully and to do the recommended deep gravel vacs to clean up paralyzed parasites. One added benefit of treating with Levamisole is that it gives the immune system a boost and the fish may appear to be healthy suddenly.