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No Thumbnail AvailableProjectInvestigations in freshwater fish culture, India 1985
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No results found.This report was prepared during the course of the project identified on the title page. The conclusions and recommendations given in the report are those considered appropriate at the time of its preparation. They may be modified in the light of further knowledge gained at subsequent stages of the project. The designations employed and the presentation of the material in this document do not imply the expression of any opinion whatsoever on the part of the United Nations or the Food and Agricu lture Organization of the United Nations concerning the legal or constitutional status of any country, territory or sea area, or concerning the delimitation of frontiers. -
No Thumbnail AvailableProjectEnvironmental diel cycle during mass fish kills and planktonic collapse in an undrainable rural fish pond
Establishment of a Network of Aquaculture Centres in Asia
1986Also available in:
No results found.With a view to find out the possible causes for the sudden occurrence of large scale mortality of fish and fish food organisms in a shallow pond of 1.25 ha on a hot summer day (June 5, 1982), the diurnal variation of physico-chemical factors and plankton density were studied. Water temperature (29.0–37.5°C), free carbon dioxide (0–32.0 ppm) and dissolved oxygen (0.08–11.6 ppm) showed marked fluctuation round the clock. Phytoplankton density was found to be maximum at 5.00 am. and minimum at 9.00 p.m. and during day time was markedly less. Volumetric estimation of plankton revealed a considerable decline in plankton biopmass (71.32%) over a period of 3 days during the hot spell (June 5–8, 1982). The computed loss in density of phytoplankters was 2981 u/1 and that of zooplankters 2354 u/1 during the period. The dead fishes included Cyprinus carpio, Cirrhinus mrigala, Catla catla and Labeo rohita. The lethal conditions for aquatic life occurred with high temperature and complete deple tion of dissolved oxygen in the day time and the sharp rise in free carbon dioxide in the night. The adverse environmental conditions were further aggravated due to very low water level, high concentration of suspensoids of particulate and colloidal matter at the pond bottom and high rate of decomposition of organic matter etc., which seem to have been cumulatively responsible for the sudden mortality of fishes and the collapse of planktonic organisms. -
No Thumbnail AvailableProjectPrimary studies on frequencies of fertilization of fish ponds
Establishment of a Network of Aquaculture Centres in Asia
1987Also available in:
No results found.One of the common practices in traditional Chinese fish culture is the utilization of animal manure in farming fish. Although qualitative and quantitative studies have been done on the principles of fish culture in manure-loaded ponds (1, 3, 4, 5), further research on the relationship between the methods of manuring and/or fertilizing and fish yields will be of help in furts er maximizing fish production
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