Overcrowded fish are more susceptible to disease and suffer more stress, aggression, and physical injuries such as fin damage. Along with lack of space, overcrowding can also lead to poor water quality, so the fish have less oxygen to breathe.

Natural behavior

The behavioral requirements of most of the fish species used in aquaculture are poorly understood. It is unlikely that the conditions in intensive farming meet even the basic needs of fish.

For example, rearing fish in cages prevents their natural swimming behaviour. Salmon are migratory, and would naturally swim great distances at sea. Instead, they swim in circles around the cage, rubbing against the mesh and each other.

Starvation

Food is often withheld from farmed fish before a stressful procedure, such as transport or grading (sorting into groups of similar size), and slaughter. No more than two or three days are normally needed to empty the gut, but some fish may be starved for two weeks or more.

Death by suffocation

Farmed fish are slaughtered by a range of methods. Some methods cause immense suffering, such as gassing with carbon dioxide or cutting the gills without stunning. Some fish are simply left to suffocate in air or on ice, or may be processed while still alive. Other methods are more humane, such as electrical stunning or a strike to the head.

There are alternatives to intensive farming of fish with much higher welfare potential.

Higher welfare alternatives for fish

Higher welfare farmed fish

Fish can be farmed more humanely than conventional intensive farming. Organic standards, such as those set by the Soil Association, improve the welfare of farmed fish.

Contrary to organic standards for other animals, fish may still be confined in cages. However organic farmed fish benefit from more space and are slaughtered using more humane methods. In addition, Soil Association organic standards limit starvation periods and only allow wild fish to be used as feed for farmed fish if they were sustainably caught.

Wild-caught fish