If you are sure it is flukes, this stuff really is quite great. The main active ingredient is the same anti-worm medicine the vet subscribes to you cat or dog. It is virtually impossible to overdose -- the fish toxicity levels are something like 30-50 times the recommended dose. And, when I've used it, never seen any problem with the filter or plants. Those fluke tabs are organo-phosphate chemcials, far, far more dangerous than praziquantel. As near as I could tell, my fish didn't even notice the prazi in the water, apart from them stopping scratching.