Effect of season on oocyte development and serum steroid hormones in LHRHa and pimozide-injected catfish Clarias macrocephalus (Günther)
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Oocyte and blood samples were taken from gravid female catfish Clarias macrocephalus at 4-h intervals to monitor the stage of oocyte development and serum steroid hormone profiles after injection of luteinizing hormone-releasing hormone analogue (LHRHa) and pimozide (PIM) during the off-season (February) and the peak of the natural breeding period (August). Results showed that the onset of final oocyte maturation (12h) and ovulation (16h), and levels of serum estradiol-17β (E2) did not vary with season in LHRHa+PIM-injected fish. In February, ovulated eggs were stripped from three and two hormone-treated fish at 16h and 20h post-injection, respectively. In August, ovulation was observed in all hormone-treated females (n=5) at 16h post-injection but stripping of the eggs was possible only 4h thereafter. Serum E2 levels were significantly different only with varying time post-injection; a marked increase occurred at 12h, but the elevation was higher in fish induced to ovulate during the peak (16.8ng/ml) than off-season (7.7ng/ml). Hormone-treated fish showed higher serum testosterone (T) levels during the peak season (17-23ng/ml) than those injected during the off-season (10-20ng/ml) at 4-12h post-injection. Serum 17α, 20β-dihydroxy-4-pregnene-3-one (DHP) levels of hormone-treated fish during the off-season were only about half the level (0.29 and 0.52 ng/ml) of those treated with the same hormones during the peak season (0.54 and 0.9ng/ml) at 8 and 12h postinjection, respectively. Development of oocytes and serum steroid hormone profiles after LHRHa+PIM-induced ovulation provide basic understanding of the processes that mediate final oocyte maturation and ovulation in captive C. macrocephalus.
CitationTan-Fermin, J. D., Marte, C. L., Ueda, H., Adachi, S., & Yamauchi, K. (1999). Effect of season on oocyte development and serum steroid hormones in LHRHa and pimozide-injected catfish Clarias macrocephalus (Günther).
PublisherJapanese Society of Fisheries Science
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Ovarian development and serum steroid hormone profiles in hatchery-bred female catfish Clarias macrocephalus (Gunther) during an annual reproductive cycle JD Tan-Fermin, S Ijiri, H Ueda, S Adachi & K Yamauchi -
Fisheries Science, 1997 - Japanese Society of Fisheries ScienceOvarian development e.g. gonadosomatic index, oocyte diameter, fecundity, histology, and related steroid hormones e.g. testosterone (T), estradiol-17 β (E2), 17α, 20 β-dihydroxy-4-pregnen-3-one (DHP), were examined in captive female catfish Clarias macrocephalus during an annual cycle to establish the optimum season for its artificial propagation. Results showed that captive C. macrocephalus had a group-synchronous pattern of ovarian development, as indicated by the presence of oocytes at all stages of development throughout the annual cycle. Mean gonadosomatic index (GSI; 11-13%), oocyte diameter (1.54-1.56 mm), fecundity (80-110 eggs/g body weight), and serum T levels (36-37 ng/mL) were lowest in January-April, suggesting that it is not the optimum season to induce C. macrocephalus to spawn during these months. Serum E2 levels were lowest in January (7 ng/mL), and highest in December (20 ng /mL). Serum DHP levels were below detectable limits (<0.02 ng/mL) throughout the year, supporting the observation that final maturation and ovulation do not occur in this species under captive conditions. Changes in various reproductive parameters and steroid hormone levels indicate that January-March, April-June, July-September and October-December correspond to the refractory, preparatory, spawning and post-spawning periods, respectively, of the annual cycle. The results of the present investigation can be used as a guide for the controlled breeding and commercial aquaculture of C. mucrocephalus in the Philippines.
Dietary administration of dehydroepiandrosterone hormone influences sex differentiation of hybrid red tilapia (O. niloticus x O. mossambicus) larvae AH Mohamed, RFM Traifalgar, AE Serrano Jr., JP Peralta & FL Pedroso -
Journal of Fisheries and Aquatic Science, 2012 - Academic Journals, New YorkEffects of a steroid hormone Dehydroepiandrosterone (DHEA) on sex differentiation of hybrid red Tilapia Oreochromis niloticus x O. mossambicus larvae were investigated. Three day-old tilapia larvae were fed diets supplemented with varying concentrations of DHEA (0, 20, 40, 80 and 160 mg kg-1 feed) for 24 days. A positive control group fed with diet containing 60 mg kg-1 of 17α-methyl testosterone was also included in the experimental run. Results indicate that among the DHEA treatment groups, larvae fed with 160 mg kg-1 DHEA showed the highest percentage of males that is comparable to the number of differentiated male fish observed in treatment group receiving the 17α-methyl testosterone as the positive control group. DHEA supplementation also improves weight gain and enhances feed conversion ratio. These findings suggest that DHEA can be used as a dietary supplement to induce masculinization and can improve the growth performance of tilapia larvae.
Conference paperMN Duray - In F Lacanilao, RM Coloso & GF Quinitio (Eds.), Seminar-Workshop on Aquaculture Development in Southeast Asia and Prospects for Seafarming and Searanching; 19-23 August 1991; Iloilo City, Philippines., 1994 - Aquaculture Department, Southeast Asian Fisheries Development CenterStudies on sea bass (Lates calcarifer) broodstock were directed at techniques to maximize egg production. Now known are the: optimum luteinizing hormone releasing hormone analogue (LHRHa) dose range to induce spawning, optimum egg size responsive to LHRHa induction, appropriate time for induction, proper storage conditions for LHRHa, and induction of spermiation in males. Gonadal maturation and spawning are successfully induced by LHRHa and/or 17 alphamethyltestosterone. An experiment on photoperiodic induction of sexual maturation is being conducted to produce seed year round. Increased information on larval morphology and physiology of sea bass led to improvements in feeding strategies and transport techniques. Studies on nutrient requirements and practical diets are currently being undertaken for different stages/sizes of sea bass. An economic assessment found an integrated sea bass production system viable. Studies on groupers (Epinephelus spp.) have been geared towards broodstock development including induction of sex inversion by hormonal control, intraspecific interaction, and sex control using synthetic anabolic steroids. Spontaneous maturation and successive spawnings of captive Epinephelus suillus were achieved in 1990. Larval rearing techniques used for other marine fish species were tried but with limited success. Culture techniques in ponds and floating cages using SEAFDEC-formulated diets or commercial pellets are being developed. Studies on snappers (Lutjanus spp.) have been started with the identification of species common in Panay Island.