Zebrafish are promiscuous and breed seasonally during monsoon season. Mating behavior is also heavily influenced by photoperiod, as spawning begins immediately at first light during breeding season and continues for about an hour. In order to initiate courtship about 3 to 7 males chase females and try to lead female towards a spawning site by nudging her and/or swimming around her in a tight circle or figure eight. Spawning sites consists of bare substrate that tends to be well vegetated. In captivity, gravel spawning sites are preferred to silt spawning sites. In the wild, zebrafish breed in silt-bottomed habitats. When a breeding pair reaches the spawning site, the male aligns his genital pore with the female's and begins to quiver, which causes the female to release her eggs and the male to release his sperm. The female releases 5 to 20 eggs at a time. This cycle repeats for about an hour. While the presence of female pheromones is required for initiation of courtship behavior in the male, male gonadal pheromones are required by the female for ovulation to occur. There is limited evidence for male-male competition and female mate preference.
Mating System: polygynandrous (promiscuous)
Zebrafish breed seasonally during the monsoons, which occur from April to August. Spawning has also been recorded outside wet season, suggesting that breeding may be seasonal as a result of food availability. They tend to breed in silt-bottomed and well vegetated pools. Zebrafish lay non-adhesive eggs without preparing a nest, and are considered to be group spawners and egg scatterers. Although time to hatching depends on water temperature, most eggs hatch between 48 and 72 hours after fertilization. Chorion thickness and embryo activity also impact incubation time. Zebrafish are approximately 3 mm upon hatching and are immediately independent. They are able to swim, feed, and exhibit active avoidance behaviors within 72 hours of fertilization.
Breeding interval: Zebrafish spawn every 1 to 6 days during spawning season, which occurs once yearly..
Breeding season: Zebrafish spawn during monsoon season, from April to August
Range number of offspring: 1 to 700 .
Average number of offspring: 185.
Range time to hatching: 48 to 72 hours.
Average time to independence: 0 minutes.
Key Reproductive Features: iteroparous ; seasonal breeding ; sequential hermaphrodite (Protogynous ); sexual ; induced ovulation ; fertilization (External ); broadcast (group) spawning; oviparous
Adult zebrafish provide no parental care to young. Zebrafish are independent immediately upon hatching.
Parental Investment: no parental involvement