Tilapia RAS Farming (Recirculating Aquaculture System)

Introduction: Hello fish farmers today we are here with a great information of Tilapia RAS Farming for maximum profits. Fish is known to be an efficient source of protein and it has the potential to serve the growing demand for protein sources. Cultivation of fish in intensive aquaculture systems like Recirculated Aquaculture System or RAS offers several advantages in terms of productivity, quality, and cost-efficiency.

Recirculating Aquaculture System (RAS) farming is the culture system of the future. As with other forms of animal agriculture, moving indoors offers benefits in terms of biosecurity and year-round production. However, RAS is the most technologically challenging and currently the most expensive method to raise fish. This is why it is important to do a lot of research before investing in this type of fish production system.

All culture water is fresh, with only a small quantity of salt added during transport to which causes fish to add a protection layer of slime during shipment. Water quality is maintained in the RAS through a standard recognized system process. Water from tanks is pumped to rotating biological contactors which give biofiltration, CO2 degassing and solids collection. A final stage before water return is adding oxygen with downflow bubble contactors. About 85 percent of its water is reused which needs about 1900 m3 pumped from an aquifer, to replace the 15 percent that is removed each day. Then the wastewater is loaded with solids and ammonia which is then transferred to wastewater treatment.

Culture systems that discard water after use are known as flow-through systems; while those that filter and recycle water are called recirculating aquaculture systems (RAS), recycling or water re-use systems.

The tilapia used in production is a hybrid composed mainly of Oreochromis niloticus (Nile tilapia) genes. Tilapia is one of the most predominant aquaculture fish, which is robust and fast-growing. Production costs should be kept to a minimum to be competitive.

Recirculating Aquaculture System (RAS) for Tilapia fish farming

Recirculation  Aquaculture  System  (RAS) or often called the recirculation system is an innovation culture system that appropriate to be applied to limited land and water.

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Recirculating Aquaculture System for Tilapia Fish.
Recirculating Aquaculture System for Tilapia Fish.

The aim is to improve water quality so water can be used continuously. The movement of water will cause the distribution of environmental factors in the form of temperature, oxygen, pH, and others to be evenly distributed; even the spread of food is also evenly distributed, besides the impurities and metabolic waste from fish will be carried away by the movement.

Fish grown in RAS should be supplied with all the conditions necessary to remain healthy and grow. They want a continuous supply of clean water at a temperature and dissolved oxygen content that is optimum for growth. A filtering (biofilter) system is essential to purify the water and remove or detoxify harmful waste products and uneaten feed. The fish should be fed a nutritionally-complete feed daily to encourage fast growth and high survival.

Recirculating aquaculture systems, despite earlier failures, have become more common and more economically viable because of advancements that accomplish the essential unit processes that are solids removal, biological nitrification, oxygenation, and dissolved gas management. Recirculating aquaculture systems design should accomplish these processes with less new water input in an economically sustainable manner. Sand filters have largely been replaced by better kinds of solids removal devices such as bead filters and screen filters. Granular plastic media (bead) filters have undergone extensive development and improvement and are readily obtainable from commercial suppliers. Screen filters that use rotating drums or discs are widely used. These filters remove solids well, lose little energy as water passes through them, and discharge very little water during the cleaning process.

RAS farming represents a new and unique way to farm fish. Instead of the traditional process of growing fish outdoors in open ponds, RAS rears fish at high densities, in indoor tanks with a “controlled” environment. RAS filter and clean the water for recycling back through fish culture tanks. New water is added to the tanks to make up for splash out and evaporation and for that used to flush out waste materials.

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Location flexibility for Tilapia RAS farming

RAS is particularly helpful in areas where land and water are expensive and not readily available. They need relatively small amounts of land and water. They are most appropriate in northern areas where a cold or cool climate can slow fish growth in outdoor systems and prevent year-round production. RAS gives growers who are geographically disadvantaged because of a relatively short growing season that is less than 200 days or extremely dry or desert conditions, a competitive, profitable, year-round fish production system.

They can be located close to large markets (urban areas) and thus reduce hauling distances and transportation costs. RAS farming can use municipal water supplies (dechlorination is necessary) and discharge waste into sanitary sewer systems. Nearly all species of food fish and sport fish that are normally reared in ponds including catfish, trout, and striped bass can readily be grown in high densities when confined in tank systems.

Water reuse and land conservation in Tilapia RAS farming

RAS farming conserves both water and land. They maximize production in a relatively small area of land and use a relatively very small volume of water. For example, using a RAS it is possible to produce over 100,000 pounds of fish in a 5,000 square-foot building, while 20 acres of outdoor ponds would be necessary to create an equal amount of fish with traditional open pond culture.

Similarly, since water is reused, the water volume requirements in RAS are about 20% of what conventional open pond culture demands. They will offer a promising solution to water use conflicts, water quality, and waste disposal. These concerns will continue to intensify in the future as water demand for a different variety of uses escalates.

Water used for recirculation must preferably come from a disease-free source or be sterilized before going into the system. In most cases, it is improved to use water from a borehole, a well, or something similar than to use water coming directly from a river, lake or the sea. If a treatment system for intake water needs to be installed, it will typically contain a sand filter for microfiltration and a UV or ozone system for disinfection.

RAS farming is completely contained systems that reuse most of the water from the fish holding tanks. Wastes are removed; water is treated and recycled back to the tanks. Ideally, RAS replace small percentages of the total water volume, due to some loss during waste removal and evaporation. This low replacement volume is particularly important in saltwater systems since saltwater can be more expensive and more difficult to make or obtain than freshwater.

Feeds and feeding in Tilapia RAS farming

A complete feed, containing all the essential minerals and vitamins for healthy Tilapia fish growth, and formulated specifically for the fish species being reared, is necessary for fish production in RAS. Do not substitute other animal feed for Tilapia fish feed. Even different fish species have different nutritional requirements, mainly the quality and quantity of protein needed, that must be met to optimize growth.

We recommend feeding a commercial feed of dry, floating pellets so that the feeding activity and health of the fish can be simply observed at the water surface. The size of the pellet must correspond with the size of the fish. Feed the largest pellet that the Tilapia fish will readily swallow to maximize consumption and minimize waste. To keep feed fresh, order a limited supply and store it in a cool, dry area, free of insects and rodents. In case of a liability problem with contaminated feed, it is an excellent plan to freeze small samples of each new batch of feed purchased for subsequent analysis if necessary.

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Tilapia fish generally are fed 3 to 5 percent of their body weight or all the feed that they can consume in a short period. Fish feed remaining in the tank after five minutes is seldom eaten and overfeeding can seriously degrade water quality. A good indicator of problems with water quality or disease is when fish go off feed or refuse to eat. If fish suddenly stop feeding, immediately verify for high ammonia levels, low oxygen concentrations, diseases, or other problems. Reduced feeding rates occur at high and low water temperatures. 

Temperature for Tilapia RAS farming

Tilapia fish are cold-blooded; the temperature of the water in which they live controls their body temperature. Water temperature directly affects the physiological processes of fish such as respiration rate, the efficiency of feeding, growth, behavior, and reproduction. To ensure maximum growth and minimize stress, temperatures require to be maintained in the species’ optimal range.  Indoor RAS farming allows the farm to have greater control over the temperature of the ambient air that can impact the water temperature.  Heaters and chillers can be added to RAS to keep temperature, though this is not ideal in terms of energy efficiency.

Recirculating systems for tilapia culture

Recirculating systems for tilapia culture have several benefits. They can be located in places that do not have sufficient water resources for pond aquaculture. They can be located closer to markets and infrastructure, for example, highway connections and utilities. Indoor operations protect the fish stock from seasonal changes in temperature, allowing year-round production that satisfies constant market demand.

Tilapia is a commodity of freshwater fish that is very popular with the community as consumption fish.  Tilapia fish has almost the same nutritional value as other freshwater fish. Tilapia can live in deep and wide waters and shallow waters. A feed containing 36 percent protein is used and providing a feed conversion ratio (FCR) of 1.6: 1. Genetic diversity is maintained in broodstock and throughout 10 generations, a very select Blue Ridge tilapia fish strain has emerged which is perfect for their system.

Recirculating aquaculture system (RAS) farming are closed-loop facilities that retain and treat the water within the system. The water in the RAS system flows from a fish tank through a treatment process and is then returned to the tank, hence the term recirculating aquaculture systems.

Majority of the world’s Tilapia

Productions are done using the pond systems, however, in the temperate regions; RAS farming is employed in the production due to the cold climatic conditions. This makes the production cost higher because huge capital is expended on the RAS construction and the running of other production mechanisms such as heating, pumping, and filtering of the water. A lot of countries are now using RAS in fish production; however, the production level is low compared to other forms of fish culture.

Benefits of Tilapia RAS farming

  • RAS offers fish producers a variety of important benefits over open pond culture. This RAS farming contains a method to maximize production on a limited supply of water and land, nearly complete environmental control to maximize fish growth year-round. The flexibility to locate production facilities near large markets, complete and convenient harvesting, quick and efficient disease control.
  • RAS can be of different sizes ranging from large-scale production systems (over 1 million pounds per year) to intermediate-sized systems (500,000 pounds per year), to small systems (50,000 pounds per year). They can be used as grow-out systems to make food fish or as hatcheries to produce eggs and fingerling sport fish for stocking and ornamental fish for home aquariums.

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  1. Information is power; knowledge is an instrument per excellence; passion and determination defines them all.
    Thanks for information/knowledge shared.


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