Characins (tetras, pencilfish, silver dollars) and cyprinids (barbs, danios, rasboras) belong to the egg-scattering group of freshwater tropical fish. They exercise no parental care for their eggs or their young. Egg-scatterers will easily breed in a community tank. This however puts the eggs and fry at risk of becoming the tank inhabitants' next meal. Therefore success depends on setting up a breeding tank. Here are a few tips on how to get the best results.
Prepare the breeding tank by filling it with water from the community tank.
Lay the substrate where eggs can settle and fry can hide safely from the adult breeders. A good substrate would be marbles, java moss or a breeding mesh. Fine-leaved plants work well for barbs and tetras that shimmy and scatter their eggs and milt onto the foliage.
Introduce the breeding pair into the tank and feed them regularly.
Observe the breeding pair. Barbs and danios usually spawn hundreds of eggs, while tetras have a tendency to have a small brood.
Return the adults to the community tank as soon as the eggs are laid.
Feed the newly hatched fry with green water microorganisms or infusoria. As the fry develop and grow, feed them with mashed egg yolk, powdered fry food or young brine shrimp.
Keep the breeding tank in ideal condition because successful breeding requires the best water composition and temperature. With some egg-scatterers, it's difficult to tell the male from the female. In general, mature males are smaller, slimmer and more colorful than females. Fry usually hatch in about five days.
Remember the basic rule: Never overfeed (especially the fry) because uneaten food will quickly pollute the water. Be aware of the ideal water temperature for the particular species you are breeding. Most egg-scattering fish and their fry prefer 80 degree F breeding tanks.