A thesis submitted in partial fulfillment of the requirements of the degree of Master of Science, School of Environment, Resources & Development

Thesis (M.Sc.) - Asian Institute of Technology, 1994

The use of rice bran as a supplementary food for nursing polycultures and monocultures of Nile tilapi a, common carp and silver barb fry in hap as was compared to the use of fertilizer alone. Human waste in a form of septage was used as organic fertilizer at the rate of 150 ltg COD ha day . Survival to 8 weeks of all species combinations, except the tilapia monoculture, was very poor and high variable. Survival to 4 weeks was good for all treatments but water quality, possibly exacerbated by bird predation, subsequently reduced survival of common carp and silver barb. Poor survival was correlated with low dissolved oxygen in the early morning to the most sensitive species, the silver barb. Use of septage at these rates is probably too high for nursing· carps in monoculture or polyculture but not Nile tilapia. The high tolerance of Nile tilapia to low, early morning dissolved oxygen was also indicated by the high survival and production of cleaner fish stocked outside the hapas.