Does anyone have any experience treating fish for gill flukes? I recently had a bout with them and had success using Trifon which is an organophosphate product from Kordon. However, I must have had a few eggs remaining after my treatment period was over, and then came back and are in full force! I started treating with Trifon again at the same dosage, but it is not have the same effect after 3 days that it had earlier. Does this mean that the flukes have built a resistance to it? The recommended dosage is from 0.25 to 0.75 mg/L (based on temp, acidity, and history of usage according to the bottle) and the first time around the 0.25 didn't produce results so I did the 0.50 dosage. Now, I am wondering if I need to increase it to the 0.75 (triple my starting dosage) to see improvement. That high kind of scares me, but if that is all I can do, maybe my fish will be able to handle it? I can't let the fish go on in agony like this without some sort of relief and fast! The Trifon used to give me better results that I could see in 1-2 days. But, not the case this time. I tried Praziquantel last time too, but that didn't do a thing. Only Trifon knocked the flukes down. Tonight I am going to practically tear down the tank to eliminate the organics in the gravel and possibly remove some gravel to reduce the fluke egg build up (as well as take out and sterilize aquarium accessories). It stinks, but it has to be done because I am sick of these flukes! :devil: I read that flukes can be resistant to formalin and that some fish that are all ready weak (especially if they have wounds) will not respond well to that treatment. (That formalin can get in the wounds and be toxic to the fish) So, I am leary of using that as well. The fish get mildly aggressive with Trifon, but doesn't stress them like other meds can so I may stick with using that but increase the dosage and watch them carefully and see what happens. What else can I do? Does anyone have any other recommendations for treatment?