AQUACULTURE (farming of fish under controlled conditions) is a growth industry striving to satisfy a growing market for food fish. It currently is one of the fastest growing sectors of agriculture in the India. Farm-reared fresh fish is increasing in popularity and profitability. Catfish, Desi Magur, Tilapia carp and other aquatic species are fast becoming the new “cash crops”. Growing public demand for a healthy tasty and affordable food is stimulating the “boom” in this industry. The decline in wild fish populations as a result of overharvest and water pollution has promoted the culture of farm fresh that are grown in contaminant–free waters in indoor tank systems. Indoor Recirculating Aquaculture System are land-based fish farms, which allows all year round control and delivery of fish. Whether the facility will use fresh water, brackish or marine water, an R.A.S work on the same principles. The system can achieve optimal temperature and optimal stable productions all year around, independent on seasonal variation, location, climate, and environment.
New water is added to the tanks only to make up for splash out and evaporation and for that used to flush out waste materials. In contrast, many raceway system used to grow trout are termed “open” or “flow through” system because all the water makes only one pass through the tank and then is discarded. Fish grown in RAS must be supplied with all the conditions necessary to remain healthy and grow. They need a continuous supply of clean water at a temperature and dissolved oxygen content that is optimum for growth. A filtering (biofilter) system is necessary to purify the water and remove or detoxify harmful waste products and uneaten feed. The fish must be a fed a nutrionally-complete feed on a daily basis to encourage fast growth and high survival. Recirculating aquaculture system are used in home aquaria and for fish production where water exchange is limited and the use of biofiltration is required to reduce ammonia toxicity. Other types of filtration and environmental control are often also necessary to maintain clean water and provide a suitable habitat for fish, the main benefit of RAS is the ability to reduce the need for fresh, clean water while still commercial RAS must have high fish stocking densities if RAS must have high fish stocking, densities, and many researchers are currently conducting studies to determine if RAS is viable from of intensive aquaculture.