You will need. A community tank. A separate 10 gallon breeding tank. Pebbles or marbles to cover all of the floor of the breeding tank. Sponge filter. Heater thermostat. Thermometer.
Zebera danios are very tolerant of water conditions and temperature. For breeding purposes ph 6.8, temperature of 80F. The community tank should be about 74F and ph 7.0.
The males are streamlined in appearance. The females have a wider girth, the abdomen becomes fuller when loaded with eggs.
The contrast between the males and females is most pronounced when ready to breed.
Place six mature (about the size of 1 1/2 inches) Zebrafish in the community tank in preparation for breeding.
Set up the breeding tank: A 50 watt heater, thermostat, air stone and air pump. Place enough marbles or pebbles to cover the whole tank floor. There should be 2 inches of water above the marble level. Put a little sphagnum peat moss in a fabric bag to soften and acidify the water.
For conditioning, feed them a variety of live and flake food 4 times a day until you see that the females become egg laden with swollen abdomens. This should take 2-3 weeks. If during this time you see any chasing of females by the slimmer males, immediately move them to the breeding tank.
Select the fattest females and most active males – two males to every female. Having this ratio of males to females will guarantee the fertilization of the eggs and stimulate the breeding process because of the competition.
Once in the breeding tank if properly conditioned, you should see breeding zebrafish within a few days. If they don’t, raise the temperature a few degrees to 80 degrees F and change 5% of the water. Wait another day, change another 5% of the water. The third day and there after just do the 5% water change.
Keep feeding them 4-5 times a day with live food until they spawn.
Once the fish are in breeding mode, the whole school spawns. The eggs are dropped by the females and the males fertilize them as they drop. Zebrafish are avid egg eaters if given the chance. The eggs falling in the gaps between the marbles protects them. Also the low water level means the eggs don’t have far to fall to reach the safety of the marbles. After an hour or two the females look thin and streamlined due to dropping their eggs. Once you are satisfied that the fish have finished breeding net all the fish and place them back into the community tank.
place an airstone in the tank set to slow bubble and does the breeding tank with methylene blue. Also top up the tank with 10% water of the same temperature every day until the tank has six inches of water or more.
It will take about eight to ten days for the eggs to hatch and the fry to become free swimming. They will find there way through the marbles on their own so just watch and wait. When you see them swimming around. At this point change 5% water a day. Put a sponge filter in the tank.
When fry become free swimming and the yolk sac is absorbed, they need to be fed.
Zebra Danio fry are too small to eat fish food so they will have to be fed infusoria. In another two weeks time they will be ready to eat baby brine shrimp and fine flake food.