Breeding Aquarium Fish - Marbles

The best way to spawn egg scatterers?

Many species of fish scatter their eggs over an area, particularly at sunrise. They then gobble up all they can find. This behaviour is typical of Characins, Barbs, and Danios, but also many other species. The basis of the marble method is to prevent the predation of the eggs after spawning by making them inaccessible to the hungry adults.
A pair or spawning group should be selected and placed in a seperate spawning tank over the marbles in the evening, and then removed the following morning. The fish should not be fed during this time, as uneaten food will also fall between the marbles and foul the tank water. Once the adults are removed, the marbles can also be removed and the eggs collected, or they can simply be left in place until they hatch, and the fry are free swimming. This is a very easy and effective method of spawning egg scattering species, and one used widely in laboratories in studies of fish such as the Zebra Danio Brachydanio rerio.