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The effects of a single administration of [D-Ser(tBu)6, Pro9-NEt]-LHRHa at high dose alone (50 µg/kg), and at constant dose (20 µg/kg) combined with different doses of the dopamine receptor antagonist Metoclopramide (5, 10, 20, 40 mg/kg) for the induction of spawning in common carp broodstocks were determined under local hatchery conditions and compared with classic carp pituitary extract (CPE, double injection) application (water temperature 24 °C). Fish injected with physiological saline (0.7% NaCl) were used as a control group. No spawning was observed in the control group or in the groups given LHRH-a combined with low (5, 10 mg/kg) doses of MET. The spawning ratio was low in the group given a high dose of LHRH-a alone (50 µg/kg), while it was high in the groups given LHRH-a combined with high (20, 40 mg/kg) doses of MET, and in the group injected with CPE. Latency period in the LHRH-a+MET groups was approximately half of that in the CPE group (14-16 and 24-26 h, respectively). There were no differences between spawned groups with respect to the spawning index of broodstocks, or the fertilization/hatching rate of eggs. It was concluded that spawning can be induced successfully in common carp broodstocks with 20 µg/kg LHRH-a+20 mg/kg MET, in a single injection, in a shorter latency period and without a negative effect on egg quality, compared to CPE treatment. This combination may be useful for more effective broodstock and hatchery management in common carp culture. [ABSTRACT FROM AUTHOR]