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, 1993

Fry from 6 different farms in Eastern Thailand were raised in 5.4 rn2 nylon blue hapas at AIT aquaculture farm, for 85 days, inorder to compare quality characteristics. The fry was of four different size categories, Tiny,Small, Medium and large with average weights and lengths respectively as follows; 0.26 ±0.02 g, and 2.66 ± 0.06 cm (tiny), 0.70 ± 0.04 g and 3.75 ± 0.07 cm (small), 1.77 ± 0.12 g and 4.90 ± 0, 11 cm (medium), 10.49 ± 0.7 g and 8.10 ± 0.14 cm (large). The stocking density was 300 fry per hapa. Results showed no significant difference (P>O.05) in weight gain between fry from the 6 farms and compared to fry from AIT farm. However, large fry had superior weight gain over medium, small and tiny. The fry started spawning 3 months after stocking, and farms 1 and 5 showed higher frequency and number of observed spawning than fry from other farms and AIT fry. However, there were no significant differences (P>O.05) in terms of time of on{u2014}set of maturation in all the treatments. Mature female gonads first appeared in week 8 (60 days after stocking) with higher frequency in fry from farms 1, 2 and 5. There was no significant difference (P>0.05) in female gonadosomatic index in all the treatments. There was no significant (P<O.05) association between the quality characteristics of the fry in terms of weight gain and on set of maturation and survival with the management systems of fry production from the 6 farms, Water quality did not exert great influence on the results, however Dissolved Oxygen declined 10 days after stocking of fry (<1.00 mg/L).