Pisciculture, also known as fish farming, is the commercial breeding of fish in fish tanks or artificial enclosures such as fish ponds. It is a type of aquaculture, which is the farming of aquatic creatures such as fish, crabs, and mollusks. Fish can be grown both in saltwater or freshwater. Pisciculture is done to obtain fish products such as food and cod liver oil. It is also a fast-growing area of animal food production. Pisciculture can use a large amount of water, and extended water purification systems allow for the reuse (recycling) of local water.