East Kolkata Wetland (EKW), a Ramsar site located in West Bengal, India is unique in the world as domestic city sewage is utilized here by the fishermen as fish feed. It is important to understand the nutrient cycling pathways of this unique ecosystem in relation to the biotic communities in order to assess its health and sustainability. This study examined plankton community structure in relation to the nutrient cycling pathways and various abiotic parameters of the sewage fed fisheries of EKW in comparison to the control ponds. RDA analysis show alkalinity and water temperature are the major environmental regulators controlling phytoplankton and zooplankton communities. Results of backward stepwise linear regression indicate dissolve carbon di-oxide and water pH play important role in gross primary production in sewage fed system. As plankton communities play an important role in transport and conversion of various carbon forms like soil organic carbon, particulate organic carbon, dissolve carbon di-oxide and soil inorganic carbon, the current study has presented a conceptual model of carbon flow in the EKW fish ponds and suggests replicability of such system elsewhere for city sewage management. © 2016, Society of Wetland Scientists.