The carbon footprint of food production plays a critical role in climate change and sustainable protein supply. This article compares aquaculture and livestock farming in terms of greenhouse gas emissions, feed efficiency, and resource use. Livestock systems, particularly ruminants, generate high emissions due to methane production, land-use change, and manure management. In contrast, aquaculture generally shows lower emissions and higher efficiency, although impacts vary by species. Shellfish and seaweed systems have the lowest environmental footprint and may contribute to carbon sequestration. Despite certain challenges, aquaculture offers a promising pathway for climate-smart protein production.