Hi Brian, firstly do you know the sex of your danios? Males tend to be more slender with a brown tint to their bodies while females have more of a blue colouring and have much deeper bodies.
I've found danios to be prolific breeders, but they do eat their own eggs and fry given half a chance. Many people will keep marbles at the bottom of their tanks when breeding which will give the eggs somewhere to fall and remain safe until they hatch.
The fry when they first hatch are very small indeed, and I never actually realised I had fry the first time until I did a waterchange and noticed the bucket of dirty tank water was full of very tiny fry!
If you are interested in breeding I would advise you to get a grow out tank to remove some of the fry to.