Yea, I know it's empty. I don't want to add too much to it, because I know the guppies will overtake the tank soon enough. I am getting live plants sooner or later, actually my friend is giving me water sprite for free.
Yes its good to keep fry tanks farely empty b/c with the frequent feedings and the amount of fry thats soon to come, the bottom will get dirty easily. I would add a floating plant and live moss, both of which my fry enjoy.