Jirachai Juntana creator Little, David C. Chairperson Machintosh, Donald J. Examination Committee Waibel, Hermann Examination Committee Overseas Development Administration (British) Scholarship Donor text series technical report th Bangkok Asian Institute of Technology 1990 continuing eng 74 p. As one component of a two part study, a survey of tilapia fry production in Udonthani province found that all private fry producers mainly produced carps, mainly Silver barb (Puntius gonionotus), mrigal (Cirrhinus migrala) and Rohu (Labeo rohita) which approximately 79.5 percent total fry production. Only a half the farms accounted for produce tilapia due to the much lower production in producing tilapia fry than carps. In mass incubation experiments with Nile tilapia at AIT, the stocking density of seed were not observable effect on hatchability and did not relate to survival to swim- up fry, however the very high stocking density of seed obtained the better hatching rate. Atleast 58,677 seed (253.72 g . )/l can be successfully incubated by using the down-welling incubator made from plastic solf- drink bottle. There were not significantly different in hatchability and survival to swim-up fry but highly significant difference in weight of seed ,hatched fry and swim-up fry between broodfish classes (Small, Medium and large). Hatchability, hatched fry weight, swim-up fry weight and survival to swim- up fry were highly relationship to seed weight (r = 0.54, r = 0 . 84, r = 0.80 and r = 0.32 respectively.) and the weight of swim- up fry were also related to weight of hatched fry ( r = 0.81). Survival to swim-up fry were related to hatchability (r =0.34). Moreover there were highly significant difference in hatchability and ·survival to swim-up fry between seed stages, the greatest hatchability and survival to swim-up fry from stage 2.5. Hatchability were observable effect within the different broodfish management regime, in green water system had greater hatching rate than clear water system (P<0.05). However survival to swim-up fry were not related to the system design. A thesis submitted in partial fulfillment of the requirements for the degree of Master of science, School of Environment, Resources and Development Thesis (M.Sc.) - Asian Institute of Technology, 1990 Tilapia Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B18253 http://203.159.5.9/ait-thesis/detail.php?q=B18253 111005 20260818154506.0