Fish farming or pisciculture 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 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, tilapia, salmon, and catfish. The trouts were introduced in the country mainly to encourage Sport Fisheries. Introduction of trouts has helped the fish to become established in most of the cold water bodies of the country. Now apart from sport fisheries, culture of trouts is increasingly being identified as a commercial venture for table fish production. Two major trouts available in our waters are brown trout (Salmo Trutta fario) and rainbow trout (Salmo gairdneri gairdneri).