It has long been generally accepted that substitution between wild and farmed fish exists when they are of the same species. While this is true for some species and markets, the relation does not hold for all of them. In fact, using cointegration methodology, this paper proves that farmed and wild gilthead sea bream, sea bass and turbot (with salmon, the major European marine aquaculture species) are not substitutes in the Spanish seafood market. These results have implications for policy makers, fishers and fish farmers, stemming from ecological, economical and social sustainability.