| Author | Nguyen Cong Dan |
| Call Number | AIT Diss. no.AS-99-02 |
| Subject(s) | Tilapia--Vietnam
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| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctoral Technical Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AS-99-02 |
| Abstract | A series of studies were conducted to assess the potential of tilapia seed production under typically cool temperature of northern Vietnam. Nile tilapia brood stock of the Thai. GIFT, Egypt and Viet strains were overwintered in ponds (deep and shallow) and in hapas (deep and shallow). Large (>l g) and Small (<1 g) tilapia seed were also overwintered in deep hapas-in-ponds. When water temperature dropped below 11°C. the survival of tilapia brood fish in deep and shallow hapas-in-ponds was 99.6-100 % higher (P< 0.05) than fish stocked in deep and shallow ponds (74.4-90 0/0). The mean survival of larger fry (54 %) was also significantly higher (P: 0.05) than smaller fry (33.4 %). Daily weight gain of overwintered fingerlings of the three tilapia strains ranged between 1.8 and 2.3 g day" in both ponds and cages. The GIFT fish attained a significantly larger (P<0.0]) average individual weight compared to the Thai and Viet strains. Monosex fish of the three strains grew significantly faster (P<0.05) than mixed-sex group. Daily weight gain of new season fingerlings in ponds ranged from 1.6-1.8 g day", indicating slower growth compared to overwintered fingerlings. There was no significant difference (P>0.05) in the growth between new season mixed and monosex fish in three strains. Evaluation of the breeding performance in ricefields between brood fish overwintered in warm (T1) and cold water (T2) ponds indicated that ricefields might be used for breeding and rearing of tilapia fry. However. breeding performance (fry productivity) in T1 (0.45 fry in‘2 day'l) and T2 (0.42 fryin'2 day") was not significantly different (P> 0.05). Net profit obtained from tilapia fry and rice integratori was 107 % higher than that of single rice cropping. Financial analysis of four seed production strategies shows that a sustainable fry yield may be achieved using deep hapas-in-ponds for overwintering of brood fish (strategies 2) or overwintering of late produced fry (strategy 4). Level of loss in these strategies is about 20-30 ”/0. Meanwhile the risk of failure for the conventional strategy ranged from 30 to 50 %, this estimated net- profit was significantly lower (P<0.05) than that of other proposed strategies. The strategy 3 shows that high additional profit may be obtained from a limited warm water and rice field area. Results of these studies indicate that tilapia seed production in northern Vietnam is possible using one of these strategies. Use of hapas in deep ponds significantly improves the survival of fry and brood ftsh during the coldest months. Financial analysis also indicates the higher profit obtained from tilapia brood fish and fry overwintered in hapas-in-ponds. |
| Year | 1999 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AS-99-02 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Aquatic Systems(AS) |
| Chairperson(s) | Bart, Amrit;Mair, Graham |
| Examination Committee(s) | Demaine, Harvey;Hambrey, John;Rakshit, Sudip K.; |
| Scholarship Donor(s) | DANIDA Asian Institute of technology Aquaculture Outreach Program; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1999 |