In marine fish culture, production enhancement can be obtained through long-term projects of selective breeding to produce novel races and varieties according to the schemes of quantitative genetics and by exploiting the genetic gains from the application of innovative biomanipulation methods at zygote, gamete, chromosome and gene levels. The biotechnological approach is expected to provide additional benefits besides better performance in culture. Since it requires the enforcement of measures ensuring an effective reproductive segregation of genetically modified fish from wild conspecifics, it may promote a policy to eliminate also the present genetic contamination of feral populations by domesticated escapees. Another important advantage is the possibility of combining intergeneric hybridization, sperm cryopreservation and nuclear and gene transfer to diversify the appearance of marketed fish, while avoiding the costs and complications of setting up and selecting broodstocks of different species. In conclusion, aquatic biotechnology based on an integration of different techniques has the potential to radically transform the way mariculture industry is presently organized, to favour new strategies for market control, and to foster a more strict co-operation between fish farms, research centres, control agencies and policy-making institutions in both developed and developing countries.