Flow-Through and Recirculatory Water Systems for Fish Tanks

Enhance fish farming efficiency with sustainable water systems, reducing resource wastage and ensuring robust fish growth.

The recirculatory aquaculture system (RAS) technology is an innovative method used in fish farming that optimizes water usage by continuously recycling and purifying water within a closed-loop system. In RAS, water from the fish tanks is filtered to remove waste products and then recirculated back into the tanks, reducing the need for large volumes of fresh water. This technology enables higher fish stocking densities, leading to increased productivity and efficiency compared to traditional aquaculture methods. RAS also allows for better control of water quality parameters such as oxygen levels, temperature, and pH, resulting in healthier fish and reduced environmental impact. Overall, RAS represents a sustainable and environmentally friendly approach to fish farming that maximizes resource utilization and minimizes waste.

This technology is TAAT1 validated.

7•8

Scaling readiness: idea maturity 7/9; level of use 8/9

Adults 18 and over: Positive high

Increased employment opportunities in aquaculture management, maintenance, and system operation. Potential for entrepreneurial ventures in fish farming with reduced land and water needs.

The poor: Positive low

Opportunity for small-scale farmers to adopt sustainable fish farming, improving income and livelihoods.

Under 18: Positive medium

Improved food security by increasing fish production, providing a reliable source of affordable protein.

Women: Positive medium

Economic empowerment through involvement in aquaculture businesses, which can be managed in smaller spaces. Increased income and livelihood opportunities, contributing to household financial stability.

Climate adaptability: Highly adaptable

Allows consistent fish production in climates with fluctuating water availability

Farmer climate change readiness: Significant improvement

Prepares farmers to adapt to water and land limitations caused by climate change

Environmental health: Greatly improves environmental health

Prevents pollution of nearby ecosystems by controlling waste and nutrient discharge.

Water use: Much less water used

Recycles water, significantly reducing freshwater consumption. Requires less water compared to traditional open-pond aquaculture systems.

Problem

Limited land and water access: Traditional fish farming requires large areas and reliable water sources, limiting opportunities for aquaculture activities in resource-constrained communities.
Limited reliable water and electricity: Flow-through systems require continuous water exchange and electricity for pumping and filtration.
Poor water quality management: High fish stocking levels make it difficult to maintain suitable water quality and oxygen levels.
Fish disease risks: Poor water conditions increase stress and disease outbreaks, reducing the results of aquaculture activities.

Solution

Efficient use of limited resources: The system supports fish production in smaller spaces while recycling water, making better use of limited land and water resources.
Reduced water requirements: Water recycling reduces freshwater consumption compared with traditional open-pond systems.
Continuous water treatment: Filtration and purification remove waste and help maintain suitable conditions for fish.
Improved fish health: Regulation of water temperature, oxygen and pH reduces stress and supports healthier fish production.

Key points to design your program

Recirculating Aquaculture Systems (RAS) enable intensive fish production by continuously filtering and reusing water, reducing water consumption by up to 90% while maintaining optimal water quality and biosecurity. By maximizing fish production in limited land and water resources, the technology supports climate-smart aquaculture, urban food systems, sustainable food production, and water resource management programmes. It contributes to SDGs 2 (Zero Hunger), 6 (Clean Water and Sanitation), 11 (Sustainable Cities and Communities), and 13 (Climate Action), while creating profitable aquaculture opportunities for women, youth, and small-scale entrepreneurs in water-constrained environments.

To successfully integrate this technology, consider the following key actions :

Identify urban, peri-urban, and water-constrained production areas where limited land, water scarcity, or environmental constraints restrict aquaculture development.
Establish partnerships with WorldFish, fisheries research institutions, extension services, equipment suppliers, financial institutions, and private-sector partners to support system design, installation, and technical assistance.
Assess water availability, energy supply, site suitability, production objectives, and local technical capacity to determine the most appropriate RAS configuration and investment requirements.
Strengthen technical capacity by training technicians, producer groups, and aquaculture entrepreneurs on water quality management, dissolved oxygen, pH, ammonia and temperature monitoring, biosecurity, fish health, filtration system maintenance, and efficient system operation.
Promote integrated resource management by combining RAS with improved fish breeds such as GIFT Tilapia or Catfish, efficient feeding practices, and where appropriate, the productive use of nutrient-rich effluents for crop production.
Support local technical service ecosystems by strengthening equipment suppliers, maintenance providers, spare-parts availability, demonstration facilities, and technical advisory services to ensure reliable long-term operation.
Monitor programme performance through indicators such as water-use efficiency, stocking density, survival rates, feed conversion ratio (FCR), water quality, productivity, profitability, and technology adoption.

44000 USD

Recirculation System (130 m3) treatment

1.5—5 USD

Settling of square meter pond construction

IP

Open source / open access

Scaling Readiness describes how complete a technology's development is and its ability to be scaled. It produces a score that measures a technology's readiness along two axes: the level of maturity of the idea itself, and the level to which the technology has been used so far.

Each axis goes from 0 to 9 where 9 is the “ready-to-scale” status. For each technology profile in the e-catalogs we have documented the scaling readiness status from evidence given by the technology providers. The e-catalogs only showcase technologies for which the scaling readiness score is at least 8 for maturity of the idea and 7 for the level of use.

The graph below represents visually the scaling readiness status for this technology, you can see the label of each level by hovering your mouse cursor on the number.

Scaling readiness score of this technology

Maturity of the idea 7 out of 9

Semi-controlled environment: prototype

Level of use 8 out of 9

Used by some intended users, in the real world

Maturity of the idea										Level of use
9
8
7
6
5
4
3
2
1
	1	2	3	4	5	6	7	8	9

Countries with a green colour: Tested & adopted
Countries with a bright green colour: Adopted
Countries with a yellow colour: Tested
Countries with a blue colour: Testing ongoing

Countries where the technology is being tested or has been tested and adopted
Country	Testing ongoing	Tested	Adopted
Benin	–No ongoing testing	–Not tested	Adopted
Botswana	–No ongoing testing	–Not tested	Adopted
Burundi	–No ongoing testing	–Not tested	Adopted
Cameroon	–No ongoing testing	–Not tested	Adopted
Côte d’Ivoire	–No ongoing testing	–Not tested	Adopted
Democratic Republic of the Congo	–No ongoing testing	–Not tested	Adopted
Djibouti	–No ongoing testing	–Not tested	Adopted
Equatorial Guinea	–No ongoing testing	–Not tested	Adopted
Ethiopia	–No ongoing testing	–Not tested	Adopted
Kenya	–No ongoing testing	–Not tested	Adopted
Madagascar	–No ongoing testing	–Not tested	Adopted
Malawi	–No ongoing testing	–Not tested	Adopted
Nigeria	–No ongoing testing	–Not tested	Adopted
Rwanda	–No ongoing testing	–Not tested	Adopted
Senegal	–No ongoing testing	–Not tested	Adopted
Sierra Leone	–No ongoing testing	–Not tested	Adopted
South Sudan	–No ongoing testing	–Not tested	Adopted
Sudan	–No ongoing testing	–Not tested	Adopted
Tanzania	–No ongoing testing	–Not tested	Adopted
Uganda	–No ongoing testing	–Not tested	Adopted
Zambia	–No ongoing testing	–Not tested	Adopted
Zimbabwe	–No ongoing testing	–Not tested	Adopted

This technology can be used in the colored agro-ecological zones. Any zones shown in white are not suitable for this technology.

Agro-ecological zones where this technology can be used
AEZ	Subtropic - warm	Subtropic - cool	Tropic - warm	Tropic - cool
Arid
Semiarid
Subhumid
Humid

Source: HarvestChoice/IFPRI 2009

The United Nations Sustainable Development Goals that are applicable to this technology.

Goal 2: zero hunger

Increases fish production, contributing to food security by providing a sustainable source of protein. Enhances local food systems and reduces reliance on overfishing.

Goal 6: clean water and sanitation

Promotes efficient water use through recycling and filtration, minimizing freshwater consumption. Reduces water pollution by controlling waste discharge.

Goal 13: climate action

Helps farmers adapt to climate variability by using water-efficient and land-conserving systems.

Goal 11: sustainable cities and communities

Helps farmers adapt to climate variability by using water-efficient and land-conserving systems.

Installation:
- Set up the recirculatory system components, including tanks, filters, pumps, and aeration systems, in a suitable location.
- Ensure all connections are secure and properly sealed to prevent water leakage.
Water Preparation:
- Fill the tanks with clean water, ensuring it meets the required temperature and oxygen levels for the fish species being cultured.
Initiate the System:
- Start the recirculation system by activating the pumps. This will begin the flow of water through the filtration process.
Monitor Water Quality:
- Use water testing kits to regularly assess key parameters such as pH levels, ammonia content, and oxygen saturation.
- Adjust the system settings or make necessary changes if any parameter falls outside the recommended range.
Maintain Filtration:
- Routinely clean and maintain the filters to prevent clogging and ensure optimal filtration efficiency.
- Replace any damaged or worn-out filter components as needed.
Fish Feeding:
- Provide fish with appropriate feed based on their species and size. Monitor feeding schedules to avoid overfeeding or underfeeding.
Observe Fish Behavior:
- Regularly observe the fish for any signs of stress, illness, or abnormal behavior. Address any issues promptly.
Record Keeping:
- Maintain detailed records of water quality parameters, feed consumption, and fish growth. This information will aid in fine-tuning the system for optimal results.
Harvesting and Stocking:
- When fish reach the desired size for harvest, use appropriate methods to safely and humanely harvest them from the tanks.
- If restocking is required, ensure that new fish are acclimated to the system gradually to minimize stress.
Routine Maintenance:
- Conduct regular checks on all system components, including pumps, filters, and aeration devices. Repair or replace any faulty parts promptly.