If it has been that long then it's likely that you've encountered a prazi resistant intestinal worm. Food soaking fenbendazole (Thomas Labs Fish Bendazole) using the same method you're using for GC would be the best alternative treatment.@Humblefish @ngoodermuth I have a clown that I've been feeding GC soaked food for 3 weeks, and is still showing white stringy poop. Should I continue or use a different medication?