This article analyses the legal adaptive capacity for increasing sustainable fish aquaculture production in EU-Finland. Currently, fish aquaculture is driven by increasing global demand of fish, declining natural fisheries, food security and blue growth policies. At the same time, environmental policies such as the EU Water Framework Directive and the Marine Strategy Framework Directive set tightening legal-ecological requirements for the industry's nutrient emissions. Against this background, the success of blue growth policies related to aquaculture – and the hope of reconciling competing interests at sea – boil down to measures available for dealing with excess nutrients. In line with the mitigation hierarchy, the article establishes four alternative pathways for the fish aquaculture industry to grow without increasing its environmental nutrient footprint significantly, and evaluates the legal adaptive capacity and the legal risks attached to these pathways.