The effect of tank color and rotifer density on rotifer ingestion, growth and survival of milkfish (Chanos chanos) larvae
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The effect of tank color on rotifer ingestion, early growth and survival of milkfish larvae was assessed. The larvae were stocked at 30/L in 200-L fiberglass tanks coated black or unpainted (tan). Larvae were fed rotifers at densities of 5, 10, and 15/ml. Growth and survival were higher in black tanks than in tan tanks. Rotifers ingested were also higher in larvae reared in black tanks. In black tanks, the survival of the larvae was enhanced at high rotifer density of 15/ml. Rotifer ingestion and growth of larvae improved at higher feeding levels.
CitationDuray, M. N. (1995). The effect of tank color and rotifer density on rotifer ingestion, growth and survival of milkfish (Chanos chanos) larvae.
PublisherSan Carlos Publications, University of San Carlos
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Conference paperCL Marte & JD Toledo - In MRR Romana-Eguia, FD Parado-Estepa, ND Salayo & MJH Lebata-Ramos (Eds.), Resource Enhancement and Sustainable Aquaculture Practices in Southeast Asia: Challenges in Responsible Production … International Workshop on Resource Enhancement and Sustainable Aquaculture Practices in Southeast Asia 2014 (RESA), 2015 - Aquaculture Department, Southeast Asian Fisheries Development CenterThe basic procedures for producing marine fish fry in hatcheries developed for milkfish fry production nearly 3 decades ago are the basis of fry production systems for all other marine fish species that are now reared in hatcheries in the Philippines and other Southeast Asian countries. These include large-scale microalgae production in outdoor tanks, feeding of appropriate sized rotifer grown on microalgae such as Nannochlorum during the first feeding phase, and shifting to larger prey such as Artemia towards the latter stages of production. In recent years, the increasing demand for high-value species such as groupers, sea bass, red snapper, and pompano in both local and export markets has encouraged a number of hatcheries to produce fry to supply the requirements of fish cage farmers. Techniques are modified using information from research institutions and multi-national firms active in developing products and equipment to improve commercial production of these species. Larval feeds of appropriate sizes, forms and presentation for various larval stages incorporating essential nutrients, micronutrients, and feed stimulants are now available in the market. Diseases in marine fish hatcheries have become common occurrences such that various chemotherapeutants, vaccines, and immunostimulants are now available and increasingly being applied in fish hatcheries. Technological developments in hatchery systems, such as the use of recirculating systems, water pretreatment protocols (ozonation, mircrofiltration, UV light treatment) are also increasingly being adopted by commercial establishments. A critical link between fry production and production of marketable fish is fingerling/ juvenile production in nurseries. Fry are commonly grown in brackishwater fishponds to appropriate size for stocking in fish cages. Methods to improve growth through proper feeding and nutrition, eliminate or reduce disease occurrence and parasite infestation, reduce cannibalism in cannibalistic species such as sea bass, grouper and snappers are active areas of research. Nursery production is integrated with fry production in large commercial facilities but is also done by small-scale fish farmers who have access to fry either from the wild or hatcheries. Commercial hatcheries adopt fingerling production from well-studied species in developed countries. Smallscale farmers however still rely on zooplanktons collected from the wild such as copepods, Moina, mysids, and trash fish as feed. Production is dependent on availability of feed sources and susceptibility to pathogens and parasites that come with the feed. It can also be erratic since smallscale farms are vulnerable to changes in climate and weather conditions. Further technological advancement in marine fish hatcheries will increasingly be led by commercial establishments and industries developing equipment like photobioreactor for microalgae to produce algal paste, or methods to develop intensive systems for rotifer culture. Research institutions will however need to support the needs of the small-scale farmers and hatchery operators who may not be able to apply costly products from these companies by developing innovative simple techniques that can improve culture systems such as producing fry and fingerlings in mesocosm pond system, appropriate use of probiotics as water stabilizer, and production of zooplankton in ponds.
ArticleND Salayo -
Aquaculture Economics and Management, 2006 - International Association of Aquaculture Economics and Management (IAAEM)Uncertainties and lack of information on milkfish product prices, along with production-related problems with inputs, generally constrain efficient resource use in milkfish grow-out operations. Milkfish growers complain of fluctuating product prices such that when output price is low, they refrain from investing in inputs and technologies recommended to boosts production. The industry wants to know the state and behavior of milkfish prices. ARIMA models showed instantaneous price relationships between monthly wholesale prices in Manila and the regional producing areas. The cross-correlations of the error terms of the ARIMA models showed that prices in Manila are related with Lucena, Dagupan, Iloilo, and Zamboanga prices, but not with Cebu. Seasonal price indexes are higher (> 1) from December to May and lower (< 1) from June to November. Milkfish grow-out operators may benefit from understanding these patterns of price movements.
Milkfish (Chanos chanos) fingerling production in freshwater ponds with the use of natural and artificial feeds Milkfish fry were reared to fingerling size in freshwater ponds. For the first experiment, fish were fed the blue-green algae Oscillatoria inoculated and grown in the ponds, Oscillatoria supplemented with a fishmeal-based formulated diet, and the formulated diet alone. Twelve 50-m2 earthen ponds were prepared to enhance growth of the indigenous natural foods. Acclimated wild milkfish fry were stocked randomly at 90/m2 and were fed for 6 weeks. Milkfish fed the formulated diet alone had a significantly higher (P<0.05) mean weight gain (1.314±0.201 g) than milkfish given the combination of Oscillatoria and formulated diet (0.882±0.230 g). Growth was lowest for fish fed Oscillatoria alone. The feeding treatments in the second experiment were: combination of Spirulina powder and formulated diet, formulated diet alone, and rice bran alone. The stocking rate was equivalent to 91.5–92.5 fry/m2 and feeding lasted for 7 weeks. All feeds promoted some growth but the milkfish fed the formulated diet alone invariably had the highest weight increment (1.504±0.167 g), followed by fish given the feed combination (0.881±0.140 g). Rice bran alone gave the lowest growth response. For both pond experiments, growth trends of the young milkfish were similar to those grown under laboratory conditions. Although survival rates were significantly different in one aquarium experiment, survival rates of milkfish in ponds did not differ significantly (P>0.05) among treatments.