Farmed fish are contained - in ponds, tanks or cages - as with all farmed animals. Just as in land-based farming, farm managers increasingly choose stocking densities and handling practices that optimize growth and health status while avoiding unnecessary suffering.

Questions are sometimes raised about welfare aspects of aquaculture production. Usually, such questions focus on three issues: stocking densities, the possibility to have ‘free-range' aquaculture and the way farmed fish is slaughtered at harvest. There are many definitions of animal welfare.

One definition is based upon the Farm Animal Welfare Council's "five freedoms": Freedom from thirst, hunger and malnutrition Freedom from discomfort due to environment Freedom from pain, injury and disease Freedom to express normal behaviour for the species Freedom from fear and distress

Scientific studies have identified operating indicators of fish welfare so that producers are able to measure the welfare status of their stock. The Freedom Food certification scheme of the RSPCA in the UK is a very good example of a welfare standard that has been built by on-farm dialogue with producers and which is now available for salmonid species.