Template:Chapters 10.3
10.3 - Fish in rice paddies as a mid-season protein source
Chloe Zivot, University of Guelph, Canada
Suggested citation for this chapter.
Zivot,C. (2022) Fish in rice paddies as a mid-season protein source, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Introduction
Smallholder farmers are often hungry during mid-season prior to the crop harvest. Farming fish within rice paddies can help to alleviate this hunger and provide a valuable source of protein to smallholder households as well as organic fertilizer and other agronomic benefits for rice production. Believed to have originated in China approximately 1700 years ago (Guo, 2001), the practice of farming fish within rice paddies is still most widely observed in Asia (Halwart and Gupta, 2004). The following chapter will provide basic instructions regarding its implementation, benefits and constraints, and will provide further resources to help get started.
Implementation of rice-fish farming systems
There are two primary methods of production within rice-fish farming, namely concurrent production (characterized by the simultaneous cultivation of fish and rice within the same paddy), and rotational production (when fish and rice are grown at different times) (Halwart and Gupta, 2004). The chapter will focus primarily on concurrent production, as it is most commonly practiced (FAO, n.d.), and is considered the most efficient of the two systems in terms of water resource usage (Frei and Becker, 2005). That being said, depending on the land, growing season(s), and irrigation structure it is possible in some cases that rotational production may be more appropriate, and in some aspects more productive - please consult the additional resources provided at the end of the chapter.
Selection and preparation of land
When determining what land to use for rice-fish farming, two of the most important factors to consider are water and soil (Sollows, 2001a). In cases where the land is not evenly elevated, the selection of higher-lying land may result in a shortage of water as it will flow downwards (Sollows, 2001a). Therefore, in these cases farmers should select comparatively low-lying land (Miah et al., 2011). Yet lower-lying land is more vulnerable to flooding, therefore it is important for farmers to evaluate their ability to control flooding when selecting a location (Sollows, 2001a). Regardless, it is critical that the land selected be above maximum flood level if possible (Sollows, 2001a). Loamy or clay-based soil is ideal for rice-fish systems as it has a high water-holding capacity (Miah et al., 2011). In the event that only sandy soil is available, the farmer may have to apply manure heavily throughout the season to ensure water retention (Sollows, 2001a). An additional factor to consider is proximity of the land to the farmer’s home, as this may reduce overall time spent maintaining the paddy (Sollows, 2001a).
Generally speaking, there are four major adaptations that must be made to the rice paddy to implement concurrent rice-fish production; the creation of a refuge, the increase in height of surrounding dikes (or bunds), and the provision of screens and drains (Halwart and Gupta, 2004).
A refuge can take several forms, such as trenches, sumps or pits, and ponds. The purpose of the refuge in rice-fish system is to provide a deeper area for the fish, where they can retreat to during points in the season if/when the water level in the paddy becomes too low or dries up (Figure 1). Additionally, the refuge can be used to contain fish for further propagation as the rice is harvested, as well as to increase the convenience of harvesting the fish themselves (Halwart and Gupta, 2004). To provide fish access to the entire paddy, trenches (or canals) should be created throughout and/or around the periphery of the paddy, connecting back to the central refuge (pond, pit, or trench) (Miah et al., 2011; Bocek, n.d.). Though structure and placement of the refuge may vary, most sources recommend that the refuge be approximately 50 cm deep and 1 m wide (Halwart and Gupta, 2004; Miah et al., 2011; Bocek, n.d.), providing the fish with a sanctuary 25-30 cm below paddy level. Altogether the fish refuge(s) should only take up 5-10% of the paddy area, as to maximize rice production (Miah et al., 2011; Bocek, n.d.).
Additionally, the dikes (or bunds), or in other words the embankments surrounding the paddy, must be raised higher than they would be for solely rice culture, in order to prevent fish from escaping. Recommended dike height is between 40 centimetres (Halwart and Gupta, 2004; Bocek, n.d.) and 60 centimetres (Miah et al., 2011), and width between 40 and 50 centimeters (Halwart, 2004; Bocek, n.d.). They also must be strong enough to hold water (and prevent flooding), therefore the use of good quality clay is recommended (Bocek, n.d.).
Finally screens and (if possible) drains should be added. As the water level in the paddy must vary at different points in the season, there must be a way for water to move in and out of the paddy. In regular rice culture, farmers would create a temporary gap in the dike to allow its passage. In rice-fish culture, screens must be used to cover these openings, to prevent fish from escaping (and predatory fish or animals from entering the paddy) (Halwart and Gupta, 2004). Recommended materials to use are bamboo slats, baskets, or pieces of fish net (Halwart and Gupta, 2004). Instead of making temporary breaches in the dikes (which in rice-fish culture are larger and harder to repair) to facilitate water flow, it is highly recommended that farmers create a more permanent drain system by inserting a drain (made potentially of a bamboo tube or chute, hollow log, or pipe) (Halwart and Gupta, 2004; Sollows, 2001b). These drain pipes would require screens, as discussed above. Please refer to Figure 1 for a visual aid regarding alterations to the paddy necessary for rice-fish.
Maintenance of rice-fish systems
There are many variations within rice-fish farming systems, according to the geographical location and associated growing season, land structure, and farmers’ desired use of the fish (i.e. to sell as fingerlings, consume or sell as matured fish, etc.). As such, the following few paragraphs will provide only generalized tips for rice-fish production and the reader is encouraged to explore the more situation-specific information provided in the additional resources.
To withstand the environment of the rice paddy, fish species selected should be able to tolerate shallow water, high temperatures, low oxygen levels and high turbidity (Hora and Pillay, 1962). Those most commonly recommended are cyprinids and tilapias, most specifically the common carp, silver barb, and Nile tilapia (Halwart and Gupta, 2004; Sollows, 2001c), although research suggests that most major freshwater species can be farmed successfully (Halwart and Gupta, 2004). The choice of species is most likely to depend on regional preferences as well as access to seed, which is highly dependent on the availability of hatchery and nursery technologies (which may pose difficulties in many rural areas in the Global South) (Halwart and Gupta, 2004).
In terms of stocking, because the growing season of fish is often (but not always) limited to that of rice, usually 100 to 150 days (Halwart and Gupta, 2004), it is best to stock the fish as early as possible in order to maximize the growing season (Sollows, 2001c). Yet, it is important to make sure that the safety of the newly transplanted rice crop is not threatened in the process. While it is possible to stock small hatchlings directly after transplanting of the rice, it is safest to wait until 2 to 3 rice tillers have appeared (usually 1 to 3 weeks after transplanting or 4 to 6 weeks after direct seeding) to release fish stocks, especially in the case of large fish (Sollows and Cruz, 2001). When releasing the fish from transport bags into the paddy, the bag should be submerged in the paddy until the water temperature inside the bag is the same as that of the paddy before releasing the fish (Sollows, 2001c). It is recommended that farmers culture 2 or more fish species, as then there will less competition for food amongst the fish (as different species eat different foods) (Sollows and Cruz, 2001). It is advised that fish be stocked in the paddy at a density of 3000/ha, at which level the organic materials found in the paddy should provide sufficient food for the fish (Sollows and Cruz, 2001). At higher levels, additional feed will likely be necessary (Sollows and Cruz, 2001). Although the harvesting process varies greatly across field type, production type, and geographical location, fish are often harvested approximately a few days to a week before or after the rice has been harvested (paddy has been drained) (Miah et al., 2011; Bocek, n.d.). In terms of rice varieties, there is no knowledge of any variety that does not work with fish (Sollows and Cruz, 2001), and hence the use of local and preferred varieties should be fine. That being said, rice varieties with certain qualities are often preferred, such as those which are deep water-tolerant or that tiller rapidly (allowing fish to be stocked earlier) (Sollows and Cruz, 2001).
Benefits and constraints to adoption
Unfortunately, while it has been well documented that rice-fish farming can have widespread economic, agricultural, ecological and nutritional benefits, the practice is often underestimated and undervalued by policy-makers and development practitioners alike (Halwart and Gupta, 2004; Halwart 2006).
Food security and nutrition benefits
A primary benefit of rice-fish farming is its potential effects on food security and nutrition. As noted in the Introduction, many farm households experience increased hunger in the mid-season (sometimes referred to as the hungry season) as this period is commonly the interim between the new harvest and the depletion of food stores from the previous one (Prein and Ahmed, 2000). Practicing rice-fish farming can reduce household stress during this period as small fish can be consumed to ensure adequate food supply until the harvest. In addition to providing sustenance in times of extreme scarcity, rice-fish farming can have an important effect on household nutrition (Halwart, 2006). The consumption of fish (often eaten whole) can provide households with critical micronutrients not sufficiently found in rice, such as calcium, iron, zinc, vitamin A, as well as some fatty acids and amino acids (Halwart, 2006).
Agricultural, ecological, and economic benefits
There are many agricultural, ecological, and economic benefits to rice-fish farming. It is estimated that rice yields are increased by approximately 10% (Sollows and Cruz, 2001; Halwart and Gupta, 2004). Fish feed on weeds and many insects, greatly reducing the presence of weeds, as well as the need for both insecticides and pesticides (Halwart, 2006). Additionally, the excrement of the fish, as well as decomposition of dead fish provides nutrients to the paddy soil, which act as a natural fertilizer (Halwart and Gupta, 2004). Also, the movement of fish releases nutrients from the soil and encourages uptake by the plant (Halwart and Gupta, 2004). As a final notable benefit, studies show that rice-fish fields are better able to produce and conserve nitrogen, and fish grazing keeps pH levels lower and decreases the volatilization of ammonia (a process which can cause extreme losses in nitrogen) (Halwart and Gupta, 2004). The associated decrease in use of chemical insecticides, pesticides and fertilizers can significantly help to increase biodiversity and ecosystem health (Halwart and Gupta, 2004).
There are significant economic gains which can be observed through the practice of rice-fish farming, both at the household and macro-economic level. Research reveals that increases in net income on rice-fish farms, due to savings on pesticides and earnings on fish sales, are 7 to 65% higher than on rice monoculture farms (Halwart and Gupta, 2004). The increased practice of rice-fish farming could also have other beneficial effects on the economy, as the increased demand for labour, hatcheries and nurseries, and transportation of fish seed (amongst other forms of related employment) can contribute to national income (Halwart and Gupta, 2004).
Constraints to adoption
It is important to mention a few important constraints surrounding the implementation and practice of rice-fish farming. Firstly, the preparation of land as well as farming itself is more labour-intensive than rice monoculture (Halwart and Gupta, 2004). Although purely speculative, it is possible that if a farm household is not able to afford additional labourers, the increase in labour may fall on women and children. This could result in negative societal impacts such as lower school attendance levels and related negative future livelihood impacts.
Additionally, farmers may be resistant to adopt rice-fish farming as it restricts the use of pesticides, which they may be accustomed to using. In the event that pesticides or nitrogen rich fertilizers are applied (or accidentally enter the paddy with the flood water), due to the associated increase in the concentration of ammonia (poisonous to fish in its unionized form), death of the fish could occur (Halwart and Gupta, 2004; Sollows 2011d). This could cause a significant and devastating shock to farm household income, and fear of such an occurrence may lower adoption levels.
Picture Based Lesson to Train Farmers
Additional Resources
The resources below provide detailed descriptions of rice-fish farming practices across countries, climates, and land structures, as well as more detailed information on rice and fish species, and the benefits constraints of rice-fish culture:
Additional practical instructions for rice-fish paddy adaptations and practice:
http://www.fao.org/3/a-a0823e.pdf
http://www.fao.org/docrep/005/Y1187E/y1187e00.htm#TopOfPage
Curriculum for farmer field school on rice-fish culture
Handout for the use of NGO partners, agricultural extension officers, and other relevant actors
References
1.Bocek, A. (n.d.). Introduction to Fish Culture in Rice Paddies. International Center for Aquaculture and Aquatic Environments, Auburn University
2.FAO. (n.d.). Rice-Fish Culture System (RFC). Technologies and practices for small agricultural producers, Food and Agriculture Organization of the United Nations.
3.Frei, M. & Becker, K. (2005). Intergrated rice-fish culture: Coupled production saves resources. Natural Resources Forum, 29(2), 135-143. https://doi.org/10.1111/j.1477-8947.2005.00122.x
4.Guo, Y.(2001). Rice-fish systems in China. In Integrated agriculture-aquaculture: a primer. FAO Fisheries Technical Paper, No. 407. Retrieved from http://www.fao.org/docrep/005/Y1187E/y1187e21.htm#y
5.Halwart, M., & Gupta, M. V. (2004). Culture of Fish in Rice Fields. FAO and The WorldFish Center. Retrieved from http://www.fao.org/3/a-a0823e.pdf
6.Halwart, M. (2006). Biodiversity and nutrition in rice-based aquatic ecosystems. Journal of Food Composition and Analysis, 19(6–7), 747–751. https://doi.org/10.1016/j.jfca.2006.03.012
7.Hora, S.L., & Pillay, T.V.R. (1962). Handbook on Fish Culture in the Indo-Pacific Region. FAO Fish. Biol. Tech., (14), 203p.
8.Miah, M. A., Ali, H., & Rahman, H. (2011). Training Manual on Improved Rice-Fish Culture and Dyke Cropping. World Fish Center. Retrieved from http://pubs.iclarm.net/resource_centre/CSISA-Training-manual-rice-fish.pdf
9.Prein, M. & Ahmed, M. (2000). Integration of aquaculture into smallholder farming systems for improved food security and household nutrition. Food Nutrition Bulletin 21, 21(4), 466–471. https://doi.org/10.1177/156482650002100424
10.Sollows, J. & Cruz, C.D. (2001). Rice management in rice-fish culture. In Integrated agriculture-aquaculture: a primer. FAO Fisheries Technical Paper, No. 407. Retrieved from http://www.fao.org/docrep/005/Y1187E/y1187e30.htm#ii
11. Sollows, J. (2001a). Site selection: where to culture fish with rice?. In Integrated agriculture-aquaculture: a primer. FAO Fisheries Technical Paper, No. 407. Retrieved from http://www.fao.org/docrep/005/Y1187E/y1187e26.htm#ee
12.Sollows, J. (2001b). Preparation of field for rice-fish culture. In Integrated agriculture-aquaculture: a primer. FAO Fisheries Technical Paper, No. 407. Retrieved from http://www.fao.org/docrep/005/Y1187E/y1187e27.htm#ff
13.Sollows, J. (2001c). Stocking for rice-fish culture. In Integrated agriculture-aquaculture: a primer. FAO Fisheries Technical Paper, No. 407. Retrieved from http://www.fao.org/docrep/005/Y1187E/y1187e28.htm#gg
14.Sollows, J. (2001d). Rice-fish benefits and problems. In Integrated agriculture-aquaculture: a primer. FAO Fisheries Technical Paper, No. 407. Retrieved from http://www.fao.org/docrep/005/Y1187E/y1187e31.htm#jj