Fingerling production of hatchery-reared milkfish (Chanos chanos) in earthen nursery ponds
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Fingerling production of milkfish in ponds maybe operated as a commercial enterprise or a component of milkfish farming that comprises nursery, transition and rearing or grow-out phases. The fishpond nursery is used to grow milkfish fry to fingerlings 1-3 g in weight or 1-2 inches in length. The nursery pond is the smallest of the major fishpond compartment ranging from 500 to 5,000 m2, and is about 10% of the total farming area. The pond is prepared with utmost care to eliminate predators and competitors. The area should have good topography, is free from flooding and should have soil with good water retention properties for good dike construction and efficient culture management. Water supply should be adequate year-round and free from pollutants. Good pond water quality is maintained and natural food should be adequate to enhance growth and survival. With high stocking densities, supplemental feed is also provided. The three types of nurseries are based on feed sources: lablab, plankton with supplemental feeding and direct feeding. Select hatchery-reared fry (21 day old) that swim actively in schools, are uniform in size, have robust body, and are resistant to handling and transport stress. The ideal fry stocking density is 5-40 pieces/m2. Survival ranging from 50-90% can be expected after 25-45 days of rearing. Harvest, packing, transport, acclimation and stocking of the fry or fingerlings are carefully done during the cooler part of the day. Economic indicators show that fingerlings production is a profitable business. The improvement of milkfish grow-out technology from extensive or traditional to modified-extensive, semi-intensive and intensive culture in ponds, pens or in sea cages has increased demand for good quality fingerlings. Mass production of hatchery-reared fingerlings in earthen nursery ponds during peak season of fry availability can help bridge the supply gap. A steady supply of fingerlings for a whole year s operation will further increase production and ensure a sustainable supply of affordable market-sized fish.
PublisherAquaculture Department, Southeast Asian Fisheries Development Center
SeriesAquaculture extension manual No. 45
Format[iv], 30 p. : ill.
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Conference paperAC Emata - In TU Bagarinao & EEC Flores (Eds.), Towards sustainable aquaculture in Southeast Asia and Japan: Proceedings of the Seminar-Workshop on Aquaculture Development in Southeast Asia, Iloilo City, Philippines, 26-28 July, 1994, 1995 - Aquaculture Department, Southeast Asian Fisheries Development CenterMost of the fish research at SEAFDEC AQD in 1992-1994 was on milkfish. Studies were conducted on year-round spawning through hormonal or environmental manipulation; optimum lipid and protein levels and ration size for captive broodstock; and the influence of spawner age on reproductive performance. The economics of hatchery operations, alone or integrated with broodstock as a commercial enterprise, was assessed. Mass production of larvae was refined with the use of commercial or SEAFDEC-formulated larval diets. Alternative rearing schemes in large tanks and ponds were tried. Hatcheryproduced and wild-caught larvae were compared in terms of growth and production in experimental nursery and grow-out ponds. Supplemental diets for brackishwater grow-out culture were formulated. Studies on broodstock management of grouper Epinephelus spp. included lipid enrichment of the diet and hormonal induction of sex inversion. Seed production techniques were developed but survival rates were low. Grouper culture was found economically feasible in experimental ponds with 'trash' fish as feed. The mangrove red snapper Lutjanus argentimaculatus was successfully induced to spawn with injection of human chorionic gonadotropin. Initial larval rearing trials were successful but survival rates must be improved. Hormonal manipulation of spawning of the Asian sea bass Lates calcarifer allows seed production during most of the year. Photoperiod manipulation leads to maturation of females, but not males, beyond the natural breeding season (April-November). Nursery rearing of 9 mm juveniles is feasible in floating net cages with night lights that attract food zooplankton. The requirements of sea bass for lipid, protein, carbohydrates, and essential amino acids were determined. In the rabbitfish Siganus guttatus, weekly injections of luteinizing hormone releasing hormone analogue (LHRHa) sustains milt production for three weeks. Thyroid hormones injected into broodstocks improved the growth of larvae to day 7. Induced spawning techniques for the Asian catfish Clarias macrocephalus were refined by determining the seasonal responsiveness to LHRHa and pimozide injections and testing for pheromonal induction of spontaneous spawning. The optimum insemination rate was determined and egg hatchability was enhanced by removal of the adhesive coat before incubation. Several practical diets for catfish during grow-out culture were tested against 'trash' fish. The broodstock management for bighead carp Aristichthys nobilis was studied. Cage-reared juveniles from cage-reared broodstock showed the best growth. To improve the reproductive performance, the broodstock diets were supplemented with vitamins A, C, and E. Research on tilapias focused on genetics and strain selection. Several strain testing procedures for Nile tilapia were evaluated in their efficiency to detect economically important strain differences. Reference lines were developed from two existing red tilapia strains to measure and reduce the effects of uncontrolled nongenetic variables in strain evaluation experiments with Nile tilapia. The tolerance of two Nile tilapia strains to heavy metals was similar when gauged by the 24-hour and 96-hour lethal concentration and by fish growth, survival, and reproductive performance. In a separate study, four strains of red tilapia showed generally higher seed production when reared in tanks than in cages. Improvements in the feed and feeding management for Nile tilapia were also studied. Intensive tilapia farming and feeding have led to oxygen depletion and fish kills in Sampaloc Lake. To rehabilitate the lake, it is imperative to reduce the farming area from 30 to 6 hectares; stop the use of commercial feeds; and remove the water hyacinths and other debris. Fish kills in Laguna de Bay have also become serious in recent years, and a review of the occurrences, losses, and possible causes is currently being conducted. Studies on the epizootic ulcerative syndrome of snakeheads in Laguna de Bay have yet to pinpoint the pathogen. Skin lesions in tilapias in several ponds and lakes in the country were found to be due to bacteria.
Conference paperOK Bian - In Proceedings of the International Milkfish Workshop Conference, May 19-22, 1976, Tigbauan, Iloilo, Philippines, 1976 - Aquaculture Department, Southeast Asian Fisheries Development CenterThe paper reports the results of experimental rearing of milkfish fry in both fresh and brackishwater ponds in Sarawak. Date on the growth and survival of these imported fry are also given.
Ongoing research studies on maturation and spawning of milkfish, Chanos chanos at the brackishwater shrimp and milkfish culture applied research and training project, Jepara, Indonesia KH Alikunhi - In Proceedings of the International Milkfish Workshop Conference, May 19-22, 1976, Tigbauan, Iloilo, Philippines, 1976 - Aquaculture Department, Southeast Asian Fisheries Development CenterThe paper gives an account of the research work carried out at Jepara, Indonesia, on induction of maturity of milkfish in ponds and enclosures, and procurement of the spawners from the wild for seed production by hypophysation. Seven to eight years old pond grown milkfish were found sexually immature. Experiments are being conducted for growing and inducing maturity in 1-2 years old milkfish in fertilized ponds with regular tidal flow of water and also under regular hypophysation program. Milkfish spawners collected from sea had a few males in oozing condition and females mostly spent.