I agree with Bilbo. I have hundreds of Longfin Zebra Danios here and the hardest part is feeding the fry.
Basically all you need is a tank with heaps of moss, I mean heaps, almost so the fish cant swim through it.
feed them up on daphnia or mossies etc to get them in condition. I also used marbles to protect the falle eggs, but you can do without them if you have enough moss.
Put the adult fish in. I had two males and two females.
I just left them in there for a week and then removed them. They spawn in the morning and it is kinda obvious when they have spawned as the female lose their swollen bellies. Leave the tank for a couple of days and you should see tiny fry appear. They will usually be attached to the sides of the glass. They look like tiny slithers of glass. Shine a torch on the bottom and you should see them wriggling on the bottom.
Once they start free swimming I added a bit of green water till the tank had a slight tinge of green.
Dont panic about the food too much for the first few days but after the third day of free swimming I fed out Infusoria. The moss will provide plenty of other sustenance during feeds.
As the fry get larger you can feed them BBS and micro worms. Once they are about three weeks old you are past the hard part and they will grow fast.
Hope that helps