Study on biological performance of recombinant GnRH as a spawning – inducing agent for goldfish (Carassius auratus)

Different hormones are used to induce final sexual maturation in fish breeders and one of these hormones is different analogue of gonadotropin releasing hormone (GnRH) with different trade names. The aim of this study was to evaluate the biological activity of recombinant GnRH produced in the laboratory of Sari Agricultural Sciences and Natural Resources University on the induction and synchronization of ovulation in goldfish broodstock (Carassius auratus).  For this purpose, 20 pairs of mature goldfish were obtained from goldfish breeding centers and transferred to wet laboratory of the Fisheries Department. Fish were acclimated to experimental conditions for 2 weeks then they were divided to 4 treatments. The first, second and third groups received 10, 15 and 20 μg recombinant GnRH/kg body weight, respectively, as well as 20 mg metoclopramide (anti-dopamine)/ kg body weight and control group was injected by physiological saline with 20 mg metoclopramide (0.09% NaCl.) The results showed that the produced recombinant GnRH had the ability to induce final maturation in the studied broodstock and all groups received recombinant GnRH ovulated but none of the control group ovulated. The latency period in the broods injected by dose of 20 μg/kg was significantly lower than the other treatments (p<0.05). There was no significant difference in the total obtained egg and relative fecundity between treatments of recombinant GnRH (p<0.05). The results indicated that the recombinant GnRH has a good biological activity and it can be introduced as a suitable alternative for the treatment of reproductive disorders in goldfish.