The expression of DNA can be changed not only by changing the sequence of DNA letters, but also through epigenetics, which involves heritable changes in gene expression, for example by adding methyl groups to parts of the DNA. A new review delves deep into the implications of epigenetics for both fish and shellfish aquaculture to identify key areas of aquaculture where epigenetics could be applied. Favorable changes can be induced with no DNA selection, by manipulating the rearing environment or by selecting for epigenetic alterations. In this way, the application of epigenetic knowledge has the potential to substantially affect the productivity and sustainability of aquaculture, as well as upend traditional assumptions about selection practices. The review by SAFS postdoc Mackenzie Gavery and Prof Steven Roberts appears in the open-access journal PeerJ.