Fishing in the open seas is expensive, dangerous and increasingly difficult as some fish stocks diminish. Fish farming involves using lakes, rivers and netted-off coastal areas to raise fish that can be harvested more easily. Freshwater fish and shellfish have been most success-fully farmed in this way. Many deep-sea fish require conditions that are impossible to recreate in managed waters.
Fish farming involves raising fish commercially in tanks or enclosures such as fish ponds, usually for food. It is the principal form of aquaculture, while other methods may fall under mariculture. A facility that releases juvenile fish into the wild for recreational fishing or supplement a species’ natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species produced in fish farming are carp, tilapia, salmon, and catfish.
Demand is increasing for fish and fish protein, which has resulted in widespread overfishing in wild fisheries. China provides 62% of the world’s farmed fish. As of 2016, more than 50% of seafood was produced by aquaculture.
Farming carnivorous fish, such as salmon, does not always reduce pressure on wild fisheries. Carnivorous farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish. The 2008 global returns for fish farming recorded by the totaled 33.8 million tons worth about $US 60 billion.