While genetic selection and cultivation of organisms have helped to support a larger human population at a higher standard of living, than otherwise, these developments have also led to a loss of biodiversity, particularly in the wild. The more recent development of aquaculture continues this development process. In this note, aquaculture practices that are likely to lead to biodiversity loss are listed and their consequences are specified. Trends in fish supplies from aquaculture compared to supplies from the wild are outlined. These indicate increasing replacement of supplies form the wild by aquaculture. A similar pattern seems to be emerging as has emerged in agriculture and in silvaculture. This is likely to accelerate biodiversity loss in wild fish stocks, but it is not the only factor bringing this about. While the development of aquaculture and of genetic selection has its economic advantages, considerable uncertainty exists about how much genetic alteration is desirable from an economic point of view. More research is needed to reduce this uncertainty. Although it may be impossible to eliminate such uncertainty completely, there is scope for reducing it and improving on the rationality of our decision making.