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No Thumbnail AvailableProjectInfluence of two organochloride pesticides, Thiodan and Lindane on survival of fingerlings of Oreochromis niloticus (Linnaeus) and Tilapia zillii (Gervais)
Establishment of African Regional Aquaculture Centre
1987Also available in:
No results found.Toxic effects of two organochloride pesticides, Thiodan and Lindane on two tilapia species, Oreochromis (= Sarotherodon) niloticus and Tilapia zillii, were investigated in fresh water at 25–30°C under laboratory conditions. In the case of Thiodan LT 50 (median lethal time) values increased from 78 minutes at 1 ppm to 6.5 days at 0.001 ppm for T. zillii. As for Lindane the LT 50 values increased from 60 minutes at 2 ppm to 4.7 days at 0.125 ppm for O. niloticus while the corresponding LT 50 value s for T. zillii were 46 minutes and 2.7 days. No fish died within one week exposure at 0.0625 ppm Lindane for both O. niloticus and T. zillii. Median lethal concentrations (LC 50), obtained from regressions of pesticide concentrations and LT 50, indicated that the 96 hour LC 50's for Thiodan and Lindane were 0.00142 and 0.11590 ppm for O. niloticus, while the corresponding values were 0.00083 and 0.00597 ppm respectively for T. zillii. The safe concentration of Thiodan for O. niloticus was e stimated as 0.000588 ppm while that for T. zillii was 0.000321 ppm, and for Lindane the safe concentration was 0.0232 ppm for O. niloticus and 0.000762 ppm for T. zillii. The results showed that Thiodan was about 50 times more toxic than Lindane to O. niloticus and about 6 times more toxic than Lindane to T. zillii. -
No Thumbnail AvailableProjectInfluence of ambient oxygen on feeding and growth of the tilapia, Oreochromis niloticus (Linnaeus)
Establishment of African Regional Aquaculture Centre
1987Also available in:
No results found.Oreochromis niloticus (8.1 ± 0.5 g) grown in fresh water at 28 ± 2C for 35 days at various ambient oxygen concentrations, below air saturation in static water aquaria, were seriously affected in their feeding, assimilation and growth by ambient oxygen. While the ambient oxygen maintained was reduced from about 90% air saturation (about 7 mg/l) to about 20% air saturation (about 1.5 mg/l) food consumed and assimilated decreased 40 and 60% respectively. Correspondingly, assimilation efficiency dec reased from 80 to 50%, and conversion efficiency from 15 to 5%, while uncorrected FCR increased from 1.45 to 6.75. Under a simulated diel flux of oxygen (from about 20 to 200% air saturation) brought about by an induced bloom of plankton, growth rate of O. niloticus was considerably reduced when compared with those maintained at DO near saturation constantly. The present results suggest that DO levels below about 50% air saturation and diel flux of DO, often prevalent in tropical fish ponds tr eated with high doses of organic/inorganic fertilizers, would cause considerable reduction in pond production of tilapias. -
No Thumbnail AvailableProjectAquaculture development and coordination programme. Fish feed technology. Lectures presented at the FAO/UNDP Training Course in Fish Feed Technology, Seattle, Washington, 9 October - 15 December 1978 1980
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No results found.The need for developing suitable feeds based on locally available inexpensive ingredients has been widely recognized. Since lack of trained personnel is the main constraint in the development of fish feed technology in developing countries, the FAO/UNDP Aquaculture Development and Coordination Programme (ADCP) organized a special training course in fish feed technology at the College of Fisheries, University of Washington, Seattle, with a view to forming a small corps of fish feed specialists wh o could then be the focal points for future feed development programmes in their respective countries. The first report of the training course was presented in the report ADCP /REP/79/8. This present volume represents the edited texts of lectures presented by different specialists. Some additional material has been included for more complete coverage of the subject. Together, these texts may be considered to constitute a manual on fish feed technology, even though they were not prepared for that purpose. Twenty-six papers are included, under the general headings: (1) Digestion, physiology and anatomy; (2) nutritional bioenergetics; (3) nutritional biochemistry; (4) feedstuffs; (5) feed formulation; (6) feed manufacturing technology; (7) practical diets; and (8) quality control. Appendices include conversion tables, electrical data, and details on pelletability of selective feedstuffs, pellet die specifications, and equipment requirements for an 8 ton an hour feed mill.
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