This drug will not affect your biological filter, nor the snails or anything else. It is very specific in that it is a broad-spectrum anti-helminthic. It is actually safer to use than any other anti-helminthic on the market. You can overdose by 400% and your fish won't die. (tried it) Even the literature re: human overdoses indicates that death has been very rare and only when it was consumed in absolutely extraordinary quantities. (My CPS is at work, but I read up on it. and can't remember the exact mg/kg dose) In addition, this drug will actually assist the immune function of your fish. So, it's A-one. G. Kadar ------------------------------------------------------------------------- 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"!