Pisciculture or Fish Farming

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

Major Species according to FAO

Top ten freshwater, brackish water and marine cultured fish in 2010
Freshwater culture	Tonnage	Mariculture	Tonnage	Brackishwater culture	Tonnage
Grass carp	4,337,114	Atlantic salmon	1,421,647	Greasy grouper	3,677,691
Silver carp	4,116,835	Large yellow croaker	378,622	Flathead grey mullet	333,322
Catla (Indian carp)	3,869,984	Salmonids nei	270,436	Marine fishes nei	112,539
Common carp	3,444,203	Greasy grouper	215,028	Nile tilapia	107,489
Bighead carp	2,585,962	Sea trout	143,751	Cyprinids nei	100,000
Crucian carp	2,217,798	Japanese amberjack	139,077	Barramundi	49,234
Nile tilapia	1,990,275	Gilthead seabream	118,212	Marble goby	34,123
Pangas catfishes nei	1,305,277	Japanese seabass	107,903	Tilapias nei	23,562
Roho labeo	1,167,315	European seabass	102,538	European seabass	23,313
Freshwater fishes nei	1,080,241	Silver seabream	73,924	Mozambique tilapia	17,103
This chart is collected  from Wikipedia

Indoor fish farming

An alternative to outdoor open ocean cage aquaculture, is through the use of a recirculation aquaculture system (RAS). A RAS is a series of culture tanks and filters where water is continuously recycled and monitored to keep optimal conditions year round. To prevent the deterioration of water quality, the water is treated mechanically through the removal of particulate matter and biologically through the conversion of harmful accumulated chemicals into nontoxic ones.

Other treatments such as UV sterilization, ozonation, and oxygen injection are also used to maintain optimal water quality. Through this system, many of the environmental drawbacks of aquaculture are minimized including escaped fish, water usage, and the introduction of pollutants. The practices also increased feed-use efficiency growth by providing optimum water quality (Timmons et al., 2002; Piedrahita, 2003).

One of the drawbacks to recirculation aquaculture systems is water exchange. However, the rate of water exchange can be reduced through aquaponics, such as the incorporation of hydroponically grown plants (Corpron and Armstrong, 1983) and denitrification (Klas et al., 2006). Both methods reduce the amount of nitrate in the water, and can potentially eliminate the need for water exchanges, closing the aquaculture system from the environment. The amount of interaction between the aquaculture system and the environment can be measured through the cumulative feed burden (CFB kg/M3), which measures the amount of feed that goes into the RAS relative to the amount of water and waste discharged.