Why not farm fish in their natural environment?
The EU-funded project ClosedFishCage has developed a prototype of a sea-based cage to fulfil that purpose.
Breeding fish in this environment minimalizes production risks associated with attacks by other fish or sea lice proliferation and eliminates the need for systematic chemical cleaning.
The new technology is expected to be commercialised as of 2015.
Factsheet by the European Commission / 30 October 2012