A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Aquaculture and Aquatic Resources Management, School of Environment, Resources and Development

Thesis (M.Sc.) - Asian Institute of Technology, 2017

Present experiment was conducted in tilapia hatchery of AIT, Thailand during 13 December 2016 to 14 February 2017 to compare the growth of zooplanktons andtheir composition, and thereby the survival of Nile tilapia (Oreochromis niloticus) fry in Aquamimicry and Biofloc systems. Zooplankton populations were observed under active suspension systems by adding different carbon sources before the fry were stocked and throughout the experimental period as to control C:N ratio. In biofloc system (BS) tapioca starch was added as a carbon source and in aquamimicry system (AS) fermented rice bran was used. In Aquamimicry system higher (p<0.05) population of zooplankton was observed compared with Biofloc with linearly rising trend but sharply increased during the last period of the experiment in Biofloc. A total of 24 species of zooplankton were found in aquamimicry and 21 species in biofloc, Rotifera (58% and 70%, respectively) was the dominant group species, followed by Protozoa (38% and 23%, recpectively), Copepoda (<1% in both systems) and Cladocera (<1% in both systems).In Aquamimicry zooplankton population was associated with DO, NO2, NO3, TSS, VSS, phytoplanktondensity and floc volume but regression analysis showed only the volatile suspended solid (VSS) had direct effects on zooplankton density. In Biofloc system, DO, NH3, NO2, NO3, TSS, starch addition and floc volume had association with zooplankton population but regression analysis showed only the TSS had direct effects on the density of zooplankton. No significant differences in density and species of zooplankton of the fish guts were found.Average stocking size of Nile tilapia fry was 0.173±0.004g) and average final weights 3.82 ± 0.44 and 3.01 ± 0.23g for aquamimicry and biofloc systems respectively, with specific growth rates (SGRs) of 5.6% and 5.18% respectively. Average survival rates were 53.03±1.60 and 57.4±1.98 for aquamimicry and biofloc systems. However, these growth rates and survival were not significantly (P>0.05) different between the two systems.