RAS Business Plan, Fish Farming Question and, Answers

Introduction to RAS fish farming business plan: Well, many people have many questions about RAS fish farming especially from set up to harvesting. We are putting these questions together and try to answer them in best possible way for RAS fish business plan. Proper RAS fish business plan will result in quality fish and higher yields with maximum profits.

Frequently asked questions about RAS fish farming business plan

What is a RAS system in fish farming?

Recirculation aquaculture systems (RAS) represent a new and unique method to farm fish. 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 or biofilter system is necessary 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. RAS systems need a biological filter to process ammonia into nitrite, then nitrate.

How does a recirculating aquaculture system (RAS) work?

In recirculating aquaculture, the culture water is purified and reused continuously. The steps in the RAS system include solids removal, ammonia removal, Co2 removal, and oxygenation. Recirculating aquaculture systems 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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RAS fish farming system.
RAS fish farming system.

What are the RAS system components?

A RAS is an almost completely closed circuit. The produced waste products; solid waste, ammonium, and CO2, are removed or converted into non-toxic products by the system components. Then the purified water is subsequently saturated with oxygen and returned to the fish tanks. By recirculating the culture water, the water requirements are limited to an absolute minimum.

Most RAS system contains a mechanical filter that removes solids and a biofilter that transforms ammonia and nitrite into less toxic nitrate; these can be separate components or combined into one unit. Systems use a sterilizer- type unit to reduce the numbers of microorganisms that cause disease, as well as some form of chemical filtration to help balance different compounds in the water.

What are the benefits of the RAS aquaculture system?

  • RAS system offers fish producers a variety of important advantages over open pond culture. This is 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 and convenient harvesting, and quick and effective disease control.
  • RAS can be of various sizes ranging from large-scale production (over 1 million pounds per year) to intermediate-sized systems (500,000 pounds per year), to small systems (50,000 pounds per year). Then they can be used as grow-out systems to produce food fish or as hatcheries to produce eggs and fingerling sport fish for stocking and ornamental fish for aquariums.
  • Recirculation systems in aquaculture have stirred a great deal of interest in the field of fish farming and expanding very fast globally. The flexibility to choose the scale and module is the greatest advantage of this system, where the entrepreneur can measure and control most of the production and marketing related variables. Wide range of design and site as per geo-climatic conditions and investment capabilities. It can be used in extreme weather zone with ease.

What is the cost of RAS fish farming?

The minimum investment for a small RAS fish farming in India is estimated at approximately 4.8 lakhs for a tank measuring 1 cent. The price of the fish in the market is considered to be around Rs 250 per kg, mainly depending on the quality.

What are the types of Recirculating Aquaculture Systems?

Recirculating aquaculture systems can be divided into five types;

  1. Hatchery and grow out – Hatchery and grow out systems house younger life stages, which are more susceptible to infections. They have high stocking densities and must allow for growth, increased size, and higher feeding rates over time. These systems house one (or just a few) species per system.
  2. Breeding – Breeding systems should be designed with specific reproductive sizes, behaviors, and social structure in mind.
  3. Long-term holding – Long-term holding systems, including quarantine systems, are designed to house older juveniles, sub-adults or adults for several weeks to several months. Feeding rates are lower than in grow out or breeding systems because these fish are no longer growing rapidly.
  4. Short-term holding – These systems are common in pet stores and live-market retail and wholesale operations. Fish are generally housed for 1 to 21 days. Holding tanks and filtration should be able to handle these wide variations.
  5. Display – Display farming systems are common in public aquaria, private businesses, and homes. For these display systems, water clarity is a primary concern. It should be managed with appropriate filtration and other means to reduce suspended particulates and discoloration.

What are the different constraints of RAS?

Recirculation aquaculture system is essentially a technology for farming fish or other aquatic organisms by reusing the water in the production. The technology is based on the use of mechanical and biological filters, and the process can in principle be used for any species grown in aquaculture such as fish, shrimps, and clams, etc. The recirculation system is however primarily used in fish farming.

  • High upfront investment in materials and infrastructure.
  • Intensive technical monitoring of operations.
  • An assured but limited supply of energy for operations and good water source, preferably borehole.
  • Good fish feed quality, preferably high protein and fat extruded diets with high digestibility.

What is the difference between the RAS and the Biofloc system?

RAS systems need a biological filter to process ammonia into nitrite, then nitrate.

Biofloc system is used as a biological filter for some species. It is extraordinarily cheap to run as an aquaculture system but can kill the fish when it is not managed properly.

Explain about characteristics of recirculating aquaculture systems?

Water quality – The water in the system is recirculated through tanks and a series of water treatments to eliminate waste products. Unless the water is treated, fish will stress, resulting in retarded growth, increased predisposition to disease and lastly death. You must have a good general knowledge of the principles of water chemistry and a good knowledge of the biology of the species being cultivated.

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Tanks – Production tanks change in size and shape. Smooth, round tanks with sloping bottoms are helpful as solids can be concentrated and subsequently removed from a center drain. This design facilitates thorough cleaning and ensures aeration is distributed.

Filters – In simple recirculation systems, water can be treated by two processes: mechanical filtration and biological filtration to remove dissolved toxic wastes.

Is RAS fish farming profitable?

Due to lower sludge discharge costs and high fish density of the RAS system compared to traditional fish farming, RAS can fetch more yield of fish hence more profits.

How can you sterilize water in a RAS?

Ultraviolet (UV) units and ozone are “sterilization” components that can be used “in-line” that means as part of the circuit or a side stream loop off the circuit to kill microorganisms in the RAS water.

What is the main principle of the Recirculatory water system?

In a RAS system, the water is treated continuously to remove the waste products excreted by the fish, and oxygen is added to keep the fish alive and well. A recirculation system is quite simple. Then, from the outlet of the fish tanks the water flows to a mechanical and biological filter before it is aerated and stripped of carbon dioxide and returned to the fish tanks. Therefore, this is the basic principle of recirculation.

Do hot water recirculation pumps save money?

Demand hot water recirculating systems can save water and also energy in some situations. Recirculation systems that operate continuously have the potential to use more energy, due to energy spent pumping and hot water energy lost from the water pipes, the energy saved by reducing hot water waste. When the water reaches the desired temperature range a control turns off the pump. This procedure is similar to turning on the hot water faucet and letting the water run until it gets hot, but instead of the water going down the drain, then it is simply returned to the water heater saving energy.

What are the advantages of the RAS system?

  • RAS is an excellent use of technology to effectively manage water quality and fish welfare.
  • RAS system is easier to control the effluents and waste produced and as a farmer has less volume of wastes to deal with.
  • It is cost-effective for filtering and disinfecting farm water influents.
  • RAS system can control diseases and ensures high degree Biosecurity.
  • The system adjusts and controls production Feed Conversion Ration (FCR), Specific Growth Rate (SGR), Specific Feeding Rate (SFR).
  • The low requirement of land and water as compared to the pond aquaculture system.
  • Independence from the land-based large water source.
  • Reduction in wastewater effluent volume and the ability to closely monitor and control environmental conditions to maximize production efficiency.
  • Increased bio-security and ease in treating disease outbreaks if any.
  • High output fish from a minimal area with fish density ranging up to 50 to 150kg/m3 under perfect conditions.

There are many advantages to using recirculation technology in fish farming. Though, one major aspect to be mentioned right away is that of diseases. The impact of pathogens is lowered considerably in a recirculation aquaculture system as invasive diseases from the outside environment are minimized by the limited use of water. Water for traditional fish farming is taken from a river, a lake, which naturally increases the risk of dragging in diseases. Due to the limited use of water in recirculation the water is taken from a borehole, drainage system or spring where the risk of diseases is minimal.

What are the different fish species in the RAS system?

RAS systems are currently being used to grow catfish, striped bass, tilapia, crawfish, blue crabs, oysters, mussels, and aquarium pets. Indoor fish culture offer considerable flexibility to;

  • Grow a wide diversity of fish species,
  • Rear several different species simultaneously in the same tank (polyculture) or different tanks (monoculture),
  • Raise a variety of different sizes of one or several species to another depending on market demand and price.

RAS systems allow growers to manipulate production to meet demand throughout the year and to harvest at the most profitable times during the year. RAS permits the grower to competitively respond to market price and demand fluctuations by altering harvest rates and times and species cultured.

What are the disadvantages of the RAS system?

RAS systems do have some disadvantages when compared to open pond culture. They are expensive systems to develop (building, tanks, plumbing, biofilters) and to operate (pumping, aerating, heating, lighting). Moreover, they are complex systems and require skilled technical assistance to manage successfully.

  • The capital cost of starting a RAS is very high as compared to ponds and raceways.
  • High upfront investment in materials and infrastructure.
  • Operational cost is high due to electricity, oxygen inputs, and maintenance.
  • Highly trained staff is required to monitor and operate the system.
  • High investment at the beginning.
  • Requires qualified personnel for the design and installation of the RAS system.
  • The system requires skilled and qualified personnel for operating the farm.

Conclusion of RAS fish farming business plan

If you plan well, the RAS fish farming is commercially viable and profitable. That’s all folks about RAS fish business plan. Don’t forget to comment. You may be interested in How to Earn Money from Rabbit Farming.


  1. Hello sir,
    This prashanth.p from hyderabad …i have gone through your subject really amazing and very useful information. could you please share cost and profit analysis project report for tilapia, pangasius , carps, trouts and design of the RAS system. so that, it can be really helpful to me to start a fish production and also if possible can u please share cost analysis report for 3 variable tanks of 20000 liter capacity ..
    thanking you sir,

    with regards


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