Induced Spawning of the Indian Catfish,Heteropneustes fossilis,by GnRH Analogue Alone or in Combination with Dopamine-Affecting Drugs |
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| Abstract: | ABSTRACT Mature female Indian catfish, Heteropneustes fossilis were induced to spawn in spawning season (July-August) by various ovulation-inducing agents, and the frequency of ovulation was checked after a latency of 12-14 hours of the treatment. Egg mass and fertilization rate were taken as end-points of spawning performance. D-Ala6-Pro9] ethylamide GnRH analogue in dosages of 0.075, 0.15, 0.2, and 0.5 μg/g of body weight resulted in 28.5%, 71%, 86%, and 86% ovulation, respectively, but the lower doses of 0.01 and 0.05 μg/g body weight failed to induce ovulation in early spawning phase (July). The dopamine-2 (DA2) receptor antagonists pimozide, domperidone, and metoclopramide potentiated the anovulatory dose of 0.05 μ g GnRH analogue to induce ovulation in 86%, 86%, and 50% of the females, respectively, in the early spawning phase (July). The DA precursor, L-dihydroxyphenylalanine (L-DOPA; 10 μg/g body weight) and the DA agonist bromocriptine (10 μg/g body weight) decreased markedly the ovulatory response of 0.2 μ g GnRH analogue to 29%. The catechol-amine-synthesis inhibitor a-methylparatyrosine produced a mild depressing effect on the ovulatory response of 0.2 μ g GnRH analogue. Egg mass was high in groups that yielded a high ovulatory response (71% and above) except the a-MPT groups. The fertilization rate, however, was not affected, irrespective of the ovulatory response. The results show that the Indian catfish can be induced to spawn by superac-tive GnRH analogue alone in a dosage range of 0.15-0.2 μg/g body weight or in combination with DA2 antagonists, such as pimozide or domperidone, in a very low dosage of 0.05 μg/g. |
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| Keywords: | Indian catfish Heteropneustes fossilis induced spawning |
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