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 resources for traditional fish farming methods: Traditional fish farming often requires large expanses of land for ponds or access to natural water bodies. However, in many regions, land suitable for aquaculture is limited, and water resources may be scarce or already heavily utilized for other purposes such as agriculture or domestic use. This limitation restricts the scalability and sustainability of traditional fish farming practices.
Challenges in maintaining water quality and oxygen levels for successful fish farming: Water quality is crucial for the health and growth of fish in aquaculture systems. However, in traditional methods, maintaining optimal water quality can be challenging, especially in densely stocked ponds or areas with limited water exchange. Poor water quality can lead to stress, disease outbreaks, and reduced growth rates in fish populations, ultimately affecting farm productivity and profitability.
Need for effective waste management and control of pollutants in aquaculture systems: Aquaculture systems generate various types of waste, including uneaten feed, feces, and metabolic by-products from fish. If not managed properly, these wastes can accumulate in the water, degrade water quality, and create favorable conditions for the growth of harmful bacteria and algae. Effective waste management strategies are essential to minimize environmental impact and maintain a healthy aquatic ecosystem.
Dependence on reliable water sources and electricity infrastructure for flow-through systems: Flow-through aquaculture systems rely on continuous water exchange to maintain water quality and oxygen levels. As a result, they are highly dependent on reliable access to clean water sources, such as rivers or lakes, and electricity infrastructure to power water pumps and filtration equipment. In regions with unreliable water or electricity supply, the feasibility of implementing flow-through systems may be limited.
Importance of proper tank design and equipment selection for efficient water flow and filtration: The design of aquaculture tanks and selection of equipment play a critical role in the efficiency and effectiveness of water flow and filtration processes. Tanks must be designed to facilitate proper water circulation, oxygenation, and waste removal, while filtration equipment must be appropriately sized and configured to handle the volume and type of waste generated. Poor tank design or inadequate equipment selection can lead to inefficient water management, increased operational costs, and compromised fish health and productivity.
Challenges in regulating water temperature, oxygen levels, and pH in recirculating systems: Recirculating aquaculture systems require precise control of water parameters such as temperature, oxygen levels, and pH to maintain optimal growing conditions for fish. However, fluctuations in these parameters can occur due to factors such as environmental conditions, system dynamics, and biological processes. Achieving and maintaining proper water quality parameters in recirculating systems can be challenging and requires careful monitoring, adjustment, and management strategies to ensure fish health and productivity.

Solution

Efficient Use of Limited Resources: The technology allows for the maximum utilization of limited land and water resources by enabling higher density fish culture. This means that a greater number of fish can be raised in a smaller area compared to traditional methods, making it more efficient and sustainable.
Maintenance of Peak Water Quality: Despite dense stocking rates, the system ensures peak water quality conditions within the tanks. Through continuous filtration and purification processes, suspended matter and waste products are removed from the water, preventing the buildup of harmful substances and maintaining a healthy environment for the fish.
Continuous Water Filtration and Purification: One of the key features of the technology is its ability to continuously filter and purify water. This not only keeps the tank clean but also ensures that the water remains free from contaminants, pathogens, and excess nutrients that could negatively impact fish health.
Conversion of Waste Products: Waste products generated by the fish are either removed from the system or converted into non-toxic substances that can be used for cultivating crops. This adds an additional layer of sustainability to the system by minimizing waste and potentially creating value from by-products.
Flexibility in Location Choice: Depending on the availability of water and electricity, the technology offers flexibility in choosing the location for setting up the aquaculture system. It can be implemented in areas with reliable water sources but limited access to electricity, or vice versa, allowing for adaptation to local conditions.
Adaptability to Various Tank Designs: The technology can be adapted to different tank materials and designs, including circular and rectangular shapes. This versatility allows for customization based on specific requirements such as space availability, cost considerations, and environmental conditions.
Integration of Filtration and Conditioning Units: In recirculating systems, filtration and conditioning units are integrated into the setup to optimize water quality. These units help regulate parameters such as water temperature, oxygen levels, and nutrient concentrations, ensuring optimal conditions for fish growth and health.
Regulation of Water Parameters: The system includes mechanisms for regulating key water parameters such as temperature, oxygen levels, and pH. This ensures that the aquatic environment remains stable and conducive to fish growth, minimizing stress and promoting overall well-being.

Key points to design your project

The utilization of recirculatory aquaculture system (RAS) technology plays a crucial role in addressing poverty and enhancing food security by bolstering fish production and offering economic opportunities for fish farmers. It fosters the health of fish and mitigates environmental pollution through water recycling. Moreover, RAS stimulates job creation, encourages innovation in aquaculture, and advocates for sustainable production practices.

To incorporate this technology into your project, adhere to the following steps and prerequisites:

Evaluate the optimal water management approach for tanks based on farm conditions and investment requirements.
Obtain the necessary skills for installing and operating equipment under ideal conditions.
Conduct water quality assessments at both the source and discharge points to determine pre- and post-treatment necessities.

Estimate the required quantity of technology for your project, considering the approximate costs for recirculation pumping and piping USD 22,000 and mechanical, physical, biological, and chemical treatment USD 44,000 for a tank of 130 m3. Additionally, account for water supply and treatment costs, influenced by drainage position and type. Contractor charges for building a settling pond typically range from USD 1.5 to 5 per square meter, depending on soil type and lining materials.

Factor in delivery costs to the project site and consider import clearance and duties if applicable, as the technology is available in various countries.

Allocate resources for comprehensive training and post-training support during project implementation.

Collaborate with agricultural development institutions to promote the adoption of the technology within your country.

Explore the integration of complementary technologies such as All Male Tilapia Fingerlings with Greater Yield and Uniformity and Fast Growing and Hybrid African Catfish to enhance overall efficiency.

Cost: $$$ 22000 USD

Pumping and piping for recirculation system (130 m3)

44000 USD

Recirculation System (130 m3) treatment

1.5—5 USD

Settling of square meter pond construction

IP

Open source / open access

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

Countries where the technology has been tested and adopted
Country	Tested	Adopted
Benin	–Not tested	Adopted
Botswana	–Not tested	Adopted
Burundi	–Not tested	Adopted
Cameroon	–Not tested	Adopted
Côte d’Ivoire	–Not tested	Adopted
Democratic Republic of the Congo	–Not tested	Adopted
Djibouti	–Not tested	Adopted
Equatorial Guinea	–Not tested	Adopted
Ethiopia	–Not tested	Adopted
Kenya	–Not tested	Adopted
Madagascar	–Not tested	Adopted
Malawi	–Not tested	Adopted
Nigeria	–Not tested	Adopted
Rwanda	–Not tested	Adopted
Senegal	–Not tested	Adopted
Sierra Leone	–Not tested	Adopted
South Sudan	–Not tested	Adopted
Sudan	–Not tested	Adopted
Tanzania	–Not tested	Adopted
Uganda	–Not tested	Adopted
Zambia	–Not tested	Adopted
Zimbabwe	–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.