Fish farming is the principal form of aquaculture, while other methods of raising fish may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food and sometimes for profit.

A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species’ natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species used in fish farming are carp, salmon, tilapia and catfish.

There is an increasing demand for fish and fish protein, which has resulted in widespread overfishing in wild fisheries. Fish farming offers fish marketers another source. However, farming carnivorous fish, such as salmon, does not always reduce pressure on wild fisheries, since carnivorous farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish.