Study the artificial propagation and inducing spawning on the spotted scat by LHRHa and HCG treatment in the experiment and clam pond polycultured with Scatophagus argus, Acanthopagrus schlegelii and Rhabdosargus sarba to research the biological effects of herbivorous fish to control seaweed in clam ponds during the rearing period. Artificial propagation test were tested seven times, 127 females were processed, successful ripening (ovulation) were 91 females. The success of artificial fertilization were 66 females, Total amount of fertilized eggs was 12,155g, Buoyant egg rate were 41.5% to 71.6%, hatching rate were 6.1% to 48.4%. The experiment in the period from April to early November because the water temperature is maintained at from 21.5 ℃ to 32.5 ° C. The herbivorous fish would normal appetite to control seaweed in this temperature range, so no seaweed can grow in the pond from April to early November.