I've used metronidazole with moderate success in the the past. I quarantine affected fish then return them to my main planted tank, but it still pops up every once in a while among the cichlids & corys. I'm considering dosing my planted tank. What is metronidazole's effect on the bio filter and on plants? Any plant species particularly sensitive? Also, do you know of any medication more effective at irradicating flagellate parasites? Thanks. David Shim White stringy feces are typically a sign of Hexamita or Spironucleus infection, although other causes can not be excluded completely. Levamisole is not active on these flagellate parasites. The most appropriate first-line treatment in your case is in my opinion metronidazole, either as a 250 mg capsule/10 gal every other day for three times, or as Tetra flakes for parasites (not those for bacteria!) used for about a week. Typically these parasites are hard to eliminate, but treatment will reduce their number at least for several weeks or months. If you see no response at all, you can then suspect nematodes, and use the levamisole. I do not have the dosing data for your formulation at this time, but if you need it I can see what I have at home. Just let me know. ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@majordomo.pobox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@majordomo.pobox.com. Search http://altavista.digital.com for "Apistogramma Mailing List Archives"! ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@majordomo.pobox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@majordomo.pobox.com. Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!