The aquaculture sector plays an important role in food security, poverty alleviation and sustainable livelihoods in many developing countries. However, the positive impacts of participating in aquaculture activities, especially for small-scale producers, are hampered by lack of access to resources, distribution of risks and power asymmetries. In this study, we investigate power asymmetries and their influence on value addition in Bangladeshi value chains for pangasius and tilapia. A face-to-face survey was conducted with 1099 actors along these aquaculture value chains, the results of which suggest that power scores, power relationships and drivers of captive governance are present in the two value chains, and, in light of this, we evaluated the role played by ‘power’ in the strategic purchasing decisions of actors. Overall, we found asymmetric power scores and adverse captive governance in the relationships between farmers and feed sellers, whereas market governance and a more level competitive environment prevail in the remaining parts of the supply chain. Based on logistic regression, we identified the influential drivers of captive governance by calculating the odds ratio of significant variables. The knowledge, information and contract terms and conditions of feed sellers put them in an advantageous position over farmers.