I have a 10 gallon tank that now (after reading up on this) I realize I needed to cyle before adding fish. I started with 5 mollies and 4 have died. I need to know how do I now cyle with one fish still alive....or how do I cycle it if that molly dies as well? Do I start over and treat it like a brand new tank? I've had the tank for about 2 weeks.