As investigators for the European Food Safety Authority into the environmental risks posed by genetically modified (GM) fish, we are concerned about the US Food and Drug Administration's imminent approval of GM salmon (Nature 497, 17–18; 2013).
This is a huge step that could encourage aquaculture of other GM fish in other countries, and not necessarily under strictly biosecure conditions.
There is still considerable uncertainty surrounding the environmental and physiological effects of escaped, fast-growing GM fish on aquatic systems. This reflects a poor understanding of how different species might be affected as the modified gene is expressed in the wild.
Europe's regulatory guidelines for aquaculture of GM fish and other alien species in Europe will therefore be underpinned by rigorous risk assessment (see go.nature.com/p6x2qb).