One example of this was the Pacific oyster in the UK, which was introduced into its waters in the 1960s via aquaculture with the idea that it would be a more commercially viable species than the native oyster.
Today, many species of fish are raised in contained fresh water or ocean water environments, including salmon, catfish, tilapia, cod and others.
This density of fish creates problems like disease and pollution.
The biggest source of pollution is the accumulation of fish waste and uneaten food beneath the sea pens which can degrade the quality of the surrounding water.
The amount of pollution from fish farms also depends on how the fish are contained.
Open-net, or pen systems, allow for a direct exchange of water, where as “closed contentment” methods have a barrier which filters the water.