This antibiotic/antiprotozoan does not have as strong an effect on the biological filter bacteria as some others, but you would be much wiser to not use it in a planted tank with other fish. I have used it in a 10 gallon planted tank because my borellii was showing signs of bacterial infection on his scales. There were only the two of them in there and everything survived intact. But I would never experiment and put this stuff into a large tank full of other fish. When infestations are caught early, these drugs work. Later on, they may kill the bugs but your fish may be too debilitated to come back. 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"!