Tilapia is one of the most used species worldwide and so their productive countries are expanding quickly. Some of its specifications as low fecundity and asynchronous ovulation has made problems to tilapia hatcheries. So some efforts have done to resolve these problems. In this study the inducing effects of a single intraperitoneal injection of LHRH analog alone(20µg/kg BW) or in combination with the third generation dopamine antagonists (Olanzapine and Clozapine) in dose 5, 10 and 15 mg/kg BW were tested on ovulation induction of premature female Nile tilapia and compared with Domperidone as a well known general antagonist in treatment 20µg LHRH+10 mg Domperidone. Results showed breeding efficiency has improved in studied qualitative and quantitative indices under effect of antagonists. These results confirmed Dopaminergic inhibitory in Nile tilapia reproduction. Dopamine antagonists Accelerated and Synchronized ovulation, increased oocyte diameter, improved spawning success and enhanced ovulation index of treated fish. Also Olanzapine was more effective than clozapine and this indicate that D2 dopamine receptors have more effective role in inhibition and prolong of tilapia reproduction process and blocking these receptors is more useful than D4 receptors that probably have less impact in prevention of tilapia breeding.