What do catfish and bananas have in common? No, this is not a riddle or the start of a bad joke. Smallholder farmers know the answer: when the farmer can produce both at the same time, the by-products of bananas can enhance the growth of catfish. Producing crops and animals in this manner is part of integrated agriculture-aquaculture (IAA) farming.
Roots and tubers provide an estimated average of 20 percent of the daily per capita calorie intake for the 640 million inhabitants of Sub-Saharan Africa, where with the growing population there is increasing demand for these crops both for food and for feed. Similarly, 3.2 billion people worldwide rely on fish for almost 20 percent of their animal protein intake. IAA farming benefits developing countries smallholder farmers’ diets who can consume and have access to both vegetables and animal source protein. This farming practice alone makes for a delicious and nutritious meal in their plates and it also provides an opportunity to increase their income streams.
The CGIAR Research Program (CRP) on Fish Agri-Food Systems (FISH CRP) and on Roots, Tubers and Bananas (RTB) teamed up to investigate what is currently known about IAA systems that comprise both fish and other aquatic animals, and RTB crops. IAA systems are environmentally beneficial because of their emphasis on recycling nutrients and water through the system, however, a recent review of the literature found little scientific evidence substantiating the benefits of IAA with fish and RTB crops. The review, recently published both as a Working Paper and as an article in the International Journal of Agricultural Sustainability, found only nine studies documenting the concurrent production of fish with RTB crops. Globally, banana was the RTB crop most commonly integrated with fish production. Farmers reported taking advantage of the pond water to produce RTB crops and using the pond silt as fertilizer for the crops. The peels and leaves of the crops could also be used as feed for the fish, particularly by smallholder farmers who find commercially-produced fish feed prohibitively expensive.
Although the publications highlighted by the literature review detailed how farmers harnessed the nutrient- and water-cycling benefits of IAA systems, in subsequent interviews with stakeholders in Bangladesh, the authors noted that IAA practices are often discouraged by agriculture extension officers. Farmers in Bangladesh reported that they saw IAA practices declining over time, and some attributed this to extension officers discouraging farmers from using “traditional” IAA practices.
The review also found thirty studies investigating RTB crops residues to determine their feasibility as an ingredient in commercially-produced fish feed. Many of these studies were conducted in Nigeria, where cassava is widely consumed and there is a growing aquaculture sector. Fish feed is often cited as the biggest production cost for fish farmers and lowering the cost of fish feed through the use of locally-available agricultural waste products, such as cassava peel could boost aquaculture, especially in the small-scale sector. Using cassava peel as fish feed could potentially mitigate a growing environmental problem of agricultural waste in Nigeria. The review noted that supply issues would need to be addressed before cassava peel and other RTB crops by-products could be used at a large scale by fish feed mills.
IAA provides important environmental, social, and economic benefits to production systems, and this review is an important starting place to expand the discussion on IAA with fish and other aquatic animals and RTB, however, many knowledge gaps exist. There is significant scope and relevance to expand investigation into this topic because many smallholders who engage in aquaculture are concurrently producing RTB crops as a staple food for their households. When households have the opportunity to consume fish and RTB crops together in the same meal, they can also realize the additional nutritional benefit that comes from consuming an animal-source food that improves the nutrient bioavailability of the staple food on their plate. More research is needed to better understand how smallholders around the world use IAA systems to increase productivity, enhance their livelihoods and diversify their diets. Research is also recommended on how developing country agricultural systems can use “circular economy” concepts, such as diverting cassava peel to fish feed mills, to increase nutrient cycling and reduce waste throughout the systems.
Collaborations within the CGIAR at the CRP level, like this one between the FISH and RTB, can contribute to new thinking around how two different agricultural systems can enhance each other within a food systems framework to create greater environmental, economic and nutritional benefits for farmers, value chain actors and consumers.
The study was conducted as part of the CGIAR Research Program on Fish Agri-Food Systems led by WorldFish, together with the CGIAR Research Program on Roots, Tubers and Bananas led by the International Potato Center (CIP).