I have a 120 g also and I cycled in about 6 weeks without using fish. Some folks on the site will give you great grief for cycling with a fish in the tank. I cycled my first saltwater tank, mostly because I did not know any better, with fish and another tank without - there are critics on both sides and experts who really dont think it matters so much and do not classify as 'inhumane'. Again, you get some finatics (excuse the pun) who think your Michael Vick or someone subjecting pets to a dog fight so just recongize there is some anger out there from some when you talk about cycling a tank with a fish or two. I am not promoting the idea of cycling with a fish, but I wont criticize you for it either.