| Author | Ali, Md. Marfot |
| Call Number | AIT Thesis no. AE-95-34 |
| Subject(s) | Fish-culture
|
| Note | A thesis submitted to partial fulfillment fo the
Degree of Master of Science, School of Environment, Resources, and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Three experiments were conducted to study three stages in the seed production of silver barb
(Puntius gonionotus). The first experiment evaluated the effects of the grow-out density of
fish prior to attainment of maturity on their subsequent performance as broodfish. Two month
old fingerlings were reared for 115 days in 18 m2 nylon net cages suspended in fertilized
ponds at 5000, 10000, 20000, 30000 and 40000/ha density. Both sexes were then separated
and reared at isodensity (12 fish/cage) in the same system. After 7, 35 and 55 days broodfish
were removed for induced breeding. Higher grow-out density reduced individual size and
fecundity but this effect gradually reduced during the three spawning trials. From the
regression slope of fecundity with experimental duration, it was projected that within 80 days
of conditioning, fish initially raised at 10000 and 20000/ha would produce the same number
of eggs as fish raised at low density(5000/ha) and that fish raised at 30000 and 40000/ha
would have 11 caught up 11 with 110 days. Time latency (duration for spawning), early viability,
hatching and larvae survival were not affected by grow-out densities, indicating that egg
quality was not affected by density within the range investigated.
The second experiment compared a range of hapa materials for their performance in
the incubation of silver barb eggs in static water. A fine mesh (350-400 µm) material
normally used by commercial hatcheries in Thailand used as a control. Pure cotton with thick
soft fiber(mesh 500-700 µm), 35 % cotton: 65 % tetron fiber (mesh 600-700 µm), 65 % cotton
: 35 % polyester(mesh 250-400 µm) and pure tetron(mesh 200-300 µm) were the materials
compared. No significance differences were found among the hapa materials suggesting that,
a variety of natural, man made and combination materials in local markets throughout Asia
can be used. Variable water quality in ponds affected egg incubation.
The third experiment evaluated the value of substituting urea nitrogen with nitrogen
from legume leaf (Leucaena leucocephala) as a low-cost input for nursing silver barb in
earthen ditches(lOm * 2m * 0.8m). Five levels of substitution were compared (0% , 25%,
50 % , 7 5 % and 100 % ) . Legume leaf could be used to replace between 50 % to 7 5 % of urea.
Mean survival rates varied between 3.8-29% , but survival in trenches without snakehead
exceeded 35% . Substituting 50% of urea nitrogen with leaves resulted in similar sized fry
at harvest, SGR and net yields(0.6 g, 23.4 and 1.05 g/m2
/day respectively). Total replacement
(100%) of leaf nitrogen for urea nitrogen resulted in extremely poor survival and growth due
to poor water quality |
| Year | 1995 |
| Type | Thesis |
| 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 Food Engineering (AE) |
| Chairperson(s) | Little, David C.
|
| Examination Committee(s) | Hambrey, John B.;Sunantar Siengthai;Kamtorn Kaewpaitoon |
| Scholarship Donor(s) | The Bangladesh Government and Asian Development Bank |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1995 |