Zebra Danio Breeding

Question
I am interested in breeding Zebra Danio.  I have done some research online about different ways to go about it.  My problem is that every method I have tried has resulted in dead adult fish and no babies.  What is a simple and fool proof method to breed Zebra Danio?  The latest method that I tried was a small 5.5 gallon tank filled about 1/3 full, with marbles covering the bottom.  I also included an air stone and a small submersible heater that was preset to 78 degrees F plus minus 2 degrees.  I tested the water following the last breeding attempt.  The only test out of the ordinary was a slightly elevated NH3 level, a little under 1 ppm.  For that breeding attempt, I had placed 5 males and 5 females in the tank because I had read that Zebrafish breed in groups and that more fish will cause a breeding "frenzy." What could be resulting in the fishes' death?  This has happened three times. The fish are kept in a larger 50 gallon tank before I put them in the separate breeding tank.  I don't use tap water in either tank.  All equipment was cleaned first with an ammonia based cleaner and rinsed twice.

Answer
Hi Ryan,
5.5 gallon is a very small tank so it gives less room for error.  The reason why your NH3 (Ammonia) was elevated is because the 5.5 gallon tank is still in the cycle.  Which explains the death of your fish.  Many people are curious why, after they set up a tank, put in fish, and they die 1-2 weeks later.  For a tank to fully cycle.  You need to grow 2 sets of bacteria.  One set is the ammonia-to-nitrite converting bacteria and the other is the nitrite-to-nitrate converting bacteria.  The 50 gallon tank sounds like it has been set up for a while now, so that tank is probably cycled.  You have ammonia readings in the 5.5 gallon, which means the 1st set of bacteria has not fully grown.  And since that 1st set hasnt fully grown to produce the end result nitrite, it means the 2nd set hasnt been grown either.  For breeding purposes, it would be easier to grow foreground plants along the bottom of the 50 gallon tank for the danios to lay eggs.  The eggs will fall between the plants and will be protected from the adult fish.  But remember that it is more effective if you keep an "only species" tank, meaning only danios.  Some foreground plants that work very well are Baby Tears (HM), or Dwarf hair grass.  BUT if you want to use the breeding tank that you have.  You need to do water changes every 2 days to keep the ammonia at therepeutic levels to prevent fish deaths.
-Matt-