In this study, a cladoceran planktonic invertebrate, Moina australiensis was uniquely cultured in two stage digested piggery wastewater and fed associated piggery wastewater bacteria. The viability of M. australiensis cultured in digested piggery wastewater under closed dark conditions to limit phytoplankton activity was tested by determining suitable effluent total ammonia nitrogen (TAN) concentrations. The highest total M. australiensis biomass production 0.94 +/- 0.47 g and the rate of population increase (r) 0.15 +/- 0.08 was recorded in the 30 mg l(-1) TAN concentration treatment. The lowest 'r' values and decreased biomass production was observed with increasing TAN concentration levels, This study, also focused on profiling and quantification of the associated bacterial populations in the wastewater culture media and within the digestive tract of M. australiensis by denaturing gradient gel electrophoresis (DGGE) and real-time polymerase chain reaction (RT-PCR) which revealed the feeding specificity of M. australiensis towards "gamma- Proteobacteria." Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.