By danios, I'm assuming you mean zebra danios.
I'm not completely sure about the spawning behavior, but it could be.
As for saving fry, unless you have extremely dense plants like big piles of moss or something, you will have to remove them from the tank. Try putting large marbles in the bottom of the tank so that the eggs will fall in the cracks where the adults can't reach them. If you see any eggs or non-swimming fry, remove them with a baster or pipette or something to a different tank with a small heater and sponge filter. Having no substrate other than the marbles will make this easier.
Starting when they are free swimming, you will need to feed them. I don't know exactly what the best thing to feed them is, but I managed to crush then soak some flakes in water, then feed them the water with the suspended particles. An infusoria culture would also be good if you can get one going; google for instructions.
Once they are large enough that they can't be eaten, you can put them in the main tank.
Brian