For successful raising of zebrafish, it is recommended that the environment provided for the fish follow the following guidelines:

Use a tank with a corner or side filter and do not use gravel. The gravel tends to act like marbles by not allowing the fish to consume their eggs.
Maintain a 14 hour light / 10 hour dark cycle. The fish are photoperiodic and breed at dawn.
Keep the water temperature between 23 and 28 degrees C and a pH between 6.2 to 7.5.

For successful breeding:

In the late afternoon of the day before eggs are wanted, cover the bottom of the tank with a single layer of marbles. In the morning, after the light cycle begins and spawning has stopped, siphon the eggs from the bottom of the tank and remove the marbles. It is recommended that you do not breed the fish more than once a week. Multiple tanks will be the easiest way to get a constant supply of eggs.

Embryonic Development:

Development is dependent upon temperature and therefore can be controlled to some extent.
A simple formula for calculating stage times is
HT=h / (0.055T - 0.57)
T = development temperature
h = hours of development to reach stage at 28.5 C
HT = hours of development to reach stage at temperature T

The stages and times for each stage at 28.5 C can be seen here.