About 7 days. Zebrafish breeding cycle is the zebrafish 4 months of age into sexual maturity, 5 months of age breeding performance is better, the breeding cycle is every 7 days or so to reproduce, in a year can reproduce 6-7 times. That is to say, zebrafish generally in 4 to 5 months, can reach sexual maturity to reproduce, generally every 7 days can be spawned, the eggs after 2 to 3 days can grow into small fish.