Some Spawning Performance Parameters of Cultured Nile Tilapia Oreochromis niloticus, under Brackish Water

Tilapia is one of the most important cultured fish in the world. However, the gap between seed supplies and farmers' demand is one of the serious limitations for tilapia culturists. Notice about different effective agents on tilapia reproduction might be useful for increasing of production and better management of tilapia hatcheries. In the present study, higher efficiency of tilapia Oreochromis niloticus hatchery was considered based on the impact of sex ratio, stocking density, photoperiod, water salinity and replacement period on spawning performance. Sex r atios 1:1, 1:4 and 1:7 (Male: Female) , stocking densities 2, 3.5 and 5 fish/m 3 , photoperiods 6:18, 12:12 and 18:6 (Light:Dark), water salinities  12 , 8 , 4 and 0 ppt, also 10 and 15 days replacement of breeders were studied. F ecundity, breeder and egg per day, spawning intervals, egg diameter and weight were investigated. Results showed stocking density 5 fish/m 3 , photoperiod 12:12, 8 ppt water salinity and 10 days replacement had better performance. Sex ratio treatments had similar performance.