In order to estimate the possible scale of greenhouse gas emissions in aquaculture in Asia, this publication studies three aquaculture systems: Nile tilapia in Bangladesh, Indian major carps in India and striped catfish in Viet Nam. The analysis improves the understanding of where and how greenhouse gas emissions arise in Asian aquaculture, whilst highlighting weaknesses in the currently available data. It explains the variation at every stage of the three aquaculture systems and suggests farming methods which could potentially reduce emission intensities. The results will guide future studies on how to develop cost-effective ways of improving aquaculture performance and reducing emissions.