Yes, you get the beneficial bacterias with the live rock, but I don't know how much you have. If you have a bunch, then you are ready to put live rock in your tank. Cured live rock pretty much means that your tank is instantly cycled and ready to be stocked. but if you only got a little bit to seed your dead rocks, then you need to feed them in order to make them multiply. If you have alot of liverocks, you need to give the bacterias a food supply. so if you think your tank is instantly cycled by the rocks, then you should put a fish in there to keep feeding the bacterias, or they will just die off. I just don't know how much live rock you have.