I prefer to avoid medications for the first few days of quarantine. After a week, when the fish are comfortable and eating well, you can begin to examine them for disease. Check fresh fecal material for evidence of Capillaria , eggs or Hexamita . The fish can be netted, gently restrained with a wet cloth, then lightly scraped with a spatula to look for signs of external parasitism. Since Hexamita can be a serious problem in Discus, It may be useful to treat the fish prophylactically for the parasite, particularly if you have purchased young fish.
Treatment involves feeding a metronidazole medicated food for five days.
The food is made by pulverizing one 250 mg metronidazole tablet in one ounce of paste food. When the fish are eating switch to the medicated food for five additional days. I find this treatment effective and moderately safe for all ages of fish. The success of any treatment requires interrupting the life cycle of the parasite. A single treatment will kill the parasite and larva, but not the eggs, so within days a new infestation has started.