Author : Somsak Rungtongbaisuree

Summary : Buserelin acetate (Superfact nasal) alone or in combination with Domperidone (Motelium-M) (5-50 ug BA per kg body weight and 2-3 mg Domperidone per 1 kg) were ineffective agents for inducing spawning in O. niloticus. Spawning of O. niloticus occurred by stocking ripe females in the aquarium for 3 - 4 weeks. The eggs from stripped spawners were subjected to artificial fertilization following the dry method. Thermal shocks (11 degree C for cold shocks and 41 degree C for heat-shocks), on post fertilization time (developing egg) of 2 - 15 min for various durations of shocking at 7 - 30 min of cold shocks and 2 - 5 min of heat shocks produced triploid O. niloticus. The highest production of triploid hatchlings (64.3 percent) was derived after three minutes of heat shock treatment at 41 degree C and at five minutes post-fertilization. In cold shock treatment at 11 degree C for 30 minutes, only eight percent triploids were produced. Although some treatments also produced triploid hatchling of O. niloticus, these resulted in rather less triploids with high mortality rate.