They are egg scatterers. The male, (or several males) will chase the female vigorously around the tank and normally above some cluster of plants, their bodies will touch & they'll (briefly) vibrate in quick motion next to each other, untill they "bounce" away from each other... this is when the eggs are released..... They, and the other fish will then eat the eggs slowly falling to the bottom and only the eggs that reaches the plants & tank bottom has a chance of being hatched..... (if the bigger fish are all removed from the tank).
For a full account of their breeding methods, read the Topic "how to breed Danios".... these will also breed in that fashion.