1 Introduction

Rice-fish coculture systems can be classified according to the cultured fish species, spatial arrangements of rice cultivation and fish farming, and production management practices. Common forms include rice-carp, rice-crucian carp, rice-loach, and rice-tilapia coculture systems. Different fish species vary in feeding habits, environmental adaptability, and growth rates, and therefore require different paddy field conditions and management practices. Yuan et al. (2022) reported that common carp, grass carp, loach, and tilapia have been widely used in rice-fish coculture systems, and that species-specific ecological characteristics are important factors influencing resource utilization and aquaculture performance. In terms of production organization, rice-fish coculture can involve either the culture of a single fish species or the polyculture of different species according to their feeding habits. Inayat et al. (2023) found that rice planting density and fish species selection both influenced fish growth and overall production performance, highlighting the importance of appropriate crop-fish configuration. Furthermore, according to the layout of field facilities, traditional rice-fish coculture systems can be divided into types equipped with ditch-based or pond-based fish refuges (Arunrat and Sereenonchai, 2022). In recent years, pond-based and ex-situ rice-fish coculture systems have also been developed to improve water-use efficiency and environmental regulation through nutrient cycling between rice cultivation and aquaculture water bodies (Liu et al., 2023).

The paddy field environment is an important factor affecting fish growth performance and aquaculture benefits. Compared with conventional pond aquaculture, paddy fields generally have shallower water, and their water temperature, dissolved oxygen, and water quality are more susceptible to seasonal changes, rice growth, and field management activities. Through a systematic review, Zhu et al. (2024) identified paddy field conditions, aquaculture inputs, and field management practices as important factors affecting production performance in rice-based aquaculture systems, indicating that appropriate field infrastructure is essential for maintaining environmental stability. In practical production, fish ditches, refuge ponds, irrigation and drainage systems, and escape-prevention facilities should be properly designed according to field topography, water availability, and aquaculture scale to provide fish with sufficient space for movement and refuge. Arunrat and Sereenonchai (2022) demonstrated that both ditch-based and pond-based refuge facilities can be used in rice-fish coculture systems, although different layouts have varying implications for spatial utilization and management requirements. Meanwhile, the area occupied by fish ditches and refuge ponds should be carefully controlled to avoid excessive reduction of the rice cultivation area and potential losses in grain yield (Yuan et al., 2022). In addition, appropriate water-level regulation and drainage facilities can improve nutrient retention and water quality management while reducing nutrient losses during aquaculture production. Yang et al. (2024) demonstrated that ecological ditches combined with constructed wetlands could effectively remove certain nitrogen and phosphorus pollutants from paddy field drainage. Therefore, coordinating field infrastructure, rice growth requirements, and fish environmental needs can improve the suitability of the aquaculture environment and provide a foundation for the stable operation of rice-fish coculture systems.

The benefits of rice-fish coculture extend beyond increased fish production and economic income to encompass rice production, feed utilization, ecological conditions, and land and water resource efficiency. Previous studies have demonstrated that rice-fish coculture can improve overall paddy field productivity by promoting nutrient cycling, suppressing pests, diseases, and weeds, and reducing dependence on chemical inputs. However, ecological and economic performance varies among different coculture systems. In addition, some systems may be constrained by water-level regulation, nutrient accumulation, and greenhouse gas emissions, indicating that their ecological advantages cannot be fully realized under all production conditions. Therefore, based on existing research findings, this study systematically analyzes the effects of rice-fish coculture on fish growth performance, survival rate, aquaculture yield, and feed utilization, while comprehensively evaluating its production benefits in relation to rice yield, production costs, economic returns, product quality, and ecological conditions. Furthermore, the major factors influencing the overall benefits of rice-fish coculture, including fish species selection, stocking density, field infrastructure, and aquaculture management, are examined, and corresponding optimization strategies are proposed. This study aims to provide a theoretical basis for improving rice-fish coculture technologies, enhancing agricultural resource-use efficiency, and promoting standardized production, while offering scientific references for the green and sustainable development of agriculture.

2 Effects of the Rice-Fish Coculture System on Fish Growth Performance and Aquaculture Production

2.1 Fish growth rate and weight gain

Under rice-fish coculture conditions, fish growth rate and weight gain are jointly influenced by the paddy field environment, natural food resources, and aquaculture management practices. Compared with conventional pond aquaculture, paddy fields are characterized by shallower water, more pronounced environmental fluctuations, and more diverse food sources. Plankton, benthic organisms, and insects in paddy fields can provide natural nutrients for fish, while shading from rice plants may help alleviate heat stress. However, water temperature, dissolved oxygen, and available space in paddy fields are easily affected by rice planting density and field management practices, and unsuitable environmental conditions may suppress fish feeding activity and weight gain. Guo et al. (2020) conducted an experiment in Qingtian, Zhejiang Province, and found that fish cultured under a rice spacing of 30 cm × 30 cm achieved a specific growth rate of 4.54%/d, significantly higher than the 3.62%/d recorded under a spacing of 20 cm × 30 cm, while rice yield was maintained. Inayat et al. (2023) also found that tilapia and common carp exhibited better growth performance under medium rice planting density, with an average weight gain of 334.55 g, exceeding the 294.35 g and 270.41 g recorded under low and high planting densities, respectively. These findings indicate that appropriate rice planting arrangements can improve fish movement space and resource utilization conditions, thereby promoting fish growth.

Growth performance varies among fish species in rice-fish coculture systems and is also influenced by species combinations, stocking density, and supplementary feeding levels. Common carp and tilapia can utilize different food resources in paddy fields, but their growth rates are not necessarily identical. Inayat et al. (2023) found that, under the same rice-fish coculture conditions, tilapia achieved an average weight gain of 303.13 g, slightly higher than the 296.41 g recorded for common carp, indicating that species-specific growth characteristics influence aquaculture performance. Similarly, Lokuhetti et al. (2025) reported that tilapia exhibited better growth performance and adaptability to paddy field conditions than common carp in Sri Lanka. In addition, Ghazi and Al-Khshali (2026) found that polyculture of common carp and grass carp at an appropriate ratio resulted in higher total weight gain and specific growth rates than monoculture treatments, suggesting that combining fish species with different feeding habits may improve resource utilization efficiency. However, as stocking density increases, competition for food and movement space may intensify, potentially limiting individual weight gain. Therefore, rice-fish coculture does not necessarily improve the growth rates of all fish species, and its aquaculture advantages largely depend on the appropriate matching of fish biological characteristics with available paddy field resources (Bashir et al., 2020; Zhu et al., 2024).

2.2 Survival rate and fish yield per unit area

Fish survival rate is an important indicator for evaluating aquaculture performance in rice-fish coculture systems, directly affecting final production and economic returns. Rice plants, fish ditches, and refuge ponds in paddy fields provide fish with space for movement and shelter. However, the relatively shallow water is vulnerable to high temperatures, drought, water-level fluctuations, and pesticide application. When dissolved oxygen levels become insufficient or water quality deteriorates, fish may exhibit reduced feeding activity, impaired growth, or even mortality. Kaewpuangdee et al. (2024) found that survival rates exceeded 80% for all stocked aquatic animals in a paddy field coculture experiment involving several fish species and freshwater prawns, suggesting that properly managed paddy fields can provide relatively suitable habitats. Nevertheless, differences in fish species and stocking density can lead to substantial variations in survival rates. In a stocking-density experiment involving tilapia and common carp, Billah et al. (2020a) found that a 1:1 polyculture ratio at a stocking density of 6 fish/m² achieved a survival rate of 66.67%, higher than those recorded at densities of 4 and 8 fish/m², indicating that excessive stocking density may intensify competition and reduce survival. Lokuhetti et al. (2025) also reported an average survival rate of 74% for tilapia, compared with 64% for common carp, further demonstrating species-specific differences in adaptability to paddy field environments. Therefore, maintaining appropriate water levels, improving escape-prevention facilities, and adjusting stocking density according to fish species characteristics are essential measures for improving survival rates.

Fish yield per unit area is primarily influenced by species selection, stocking density, culture duration, and food availability. A moderate increase in stocking density can increase the number of fish per unit area, whereas excessive density may lead to food shortages, reduced dissolved oxygen, and competition for living space, thereby affecting survival and individual weight gain. Through a systematic review and meta-analysis, Fernandez-Zatrate et al. (2025) reported an average fish stocking density of approximately 13,390 fish/ha in rice-fish coculture studies, with an average fish yield of 1,383 kg/ha and an average rice yield of 4,397 kg/ha, demonstrating the potential of this system to produce both grain and aquatic products on the same land area. Hu et al. (2016) investigated integrated rice-fish farming systems in China and found that increasing fish production could improve aquaculture returns. However, rice yield began to decline when fish production exceeded approximately 2.106 t/ha in rice-common carp coculture systems, whereas keeping the area occupied by fish refuge facilities below 10% generally helped maintain rice production. Therefore, compared with high-density pond aquaculture, the primary advantage of rice-fish coculture is not simply to maximize fish yield, but to increase aquatic product output while maintaining normal rice growth. Aquaculture performance should consequently be evaluated by considering fish survival rate, average individual weight, fish yield per unit area, and rice production requirements, rather than relying solely on stocking numbers to assess overall benefits.

2.3 Feed utilization and aquaculture inputs

Rice-fish coculture systems offer certain advantages in feed utilization, primarily because they can make use of natural food resources generated within the paddy field ecosystem, thereby reducing dependence on external feed inputs. Plankton, benthic organisms, insects, and other edible organic materials in paddy fields can provide part of the nutritional requirements of cultured fish. Under appropriate stocking conditions, combining natural food resources with supplementary artificial feed can improve resource utilization. However, the abundance and nutritional composition of natural food vary with season, water quality, and stocking density, making it difficult for natural food alone to consistently meet all fish growth requirements. Zie et al. (2025), in a study of tilapia feeding in earthen ponds associated with integrated rice-fish farming, found that natural and artificial feeds accounted for approximately 48% and 52%, respectively, of the dietary intake of juvenile tilapia. In contrast, adult tilapia showed greater dependence on artificial feed, which accounted for approximately 67% of their dietary intake. These findings suggest that the relative contributions of natural and artificial food sources change with fish growth stage. However, the proportions observed in earthen pond experiments cannot be directly regarded as representative of actual feeding patterns across all paddy field aquaculture environments. Therefore, supplementary feeding in rice-fish coculture systems should be adjusted according to fish growth stage, natural food availability, and actual feeding behavior to reduce unnecessary feed consumption.

Regarding aquaculture inputs, rice-fish coculture systems can utilize existing paddy fields for production, reducing the need for additional land to construct independent aquaculture ponds. Nevertheless, costs associated with fish fingerlings, feed, field infrastructure, and management labor remain necessary, and supplementary feeding practices play an important role in determining fish growth and aquaculture returns. Billah et al. (2025) found in a tilapia-common carp polyculture experiment that final fish body weight generally increased as the daily feeding rate rose from 4% to 10% of fish body weight. However, artificial floating feed supplied at 8% of body weight per day already produced favorable growth performance and economic returns, while further increasing the feeding rate to 10% did not generate a significant additional net return. Another experiment examining feeding frequency showed that, among the treatments compared, feeding artificial floating feed twice daily, in the morning and evening, for five days per week resulted in relatively favorable fish growth performance and net returns (Billah et al., 2020b). Nevertheless, increasing feed inputs does not necessarily improve aquaculture efficiency, as excessive feeding may increase uneaten feed residues and nutrient loading in the water, thereby compromising water quality stability (Zhu et al., 2024). Therefore, evaluations of feed utilization and input efficiency in rice-fish coculture systems should consider artificial feed consumption, actual fish weight gain, survival rate, and overall aquaculture costs. By appropriately controlling stocking density, optimizing supplementary feeding, and strengthening field management, these systems can improve overall aquaculture benefits while maintaining normal fish growth.

3 Effects of the Rice-Fish Coculture System on Rice Production Benefits

3.1 Rice growth and yield performance

The rice-fish coculture system positively influences rice growth, development, and yield formation through ecological interactions between rice plants and fish. Compared with conventional rice monoculture, fish feeding, swimming, and excretion activities in paddy fields can promote nutrient cycling and organic matter decomposition, improve soil and rhizosphere conditions, and create a favorable environment for rice growth. Fish excreta and uneaten feed can release nutrients such as nitrogen and phosphorus into the paddy field through microbial decomposition, thereby improving nutrient recycling efficiency. Meanwhile, fish activity can reduce competition and damage caused by certain weeds and insect pests, contributing to improved rice nutritional status and reduced biotic stress (Kaewpuangdee et al., 2024; Fernandez-Zatrate et al., 2025). Based on a meta-analysis of 456 paired field observations, Li et al. (2022) found that the coculture of rice with aquatic animals generally improved rice yield and quality, with rice-fish coculture demonstrating relatively favorable overall production benefits. Yield improvements were particularly pronounced in subtropical regions, paddy soils with low nitrogen availability, and systems combining organic and inorganic fertilizers. These findings indicate that the positive effects of rice-fish coculture on rice growth arise not only from nutrient supplementation but also from improvements in the paddy field ecosystem and resource utilization.

The effects of rice-fish coculture on rice yield are not uniform but are jointly influenced by rice varieties, fish species, stocking density, and field management conditions. In a rice-fish coculture experiment conducted in Sri Lanka, the rice-tilapia coculture treatment achieved a grain yield of 6.7 t/ha, approximately 1.6 times that of the rice monoculture control, while the numbers of rice leaves, tillers, and panicles also increased (Lokuhetti et al., 2025). Research conducted in Arkansas, USA, also found that rice-koi coculture increased estimated rice yield, head rice recovery, and protein content, although changes in some panicle-related traits were not significant (Jia et al., 2025). In addition, appropriate rice planting density plays an important role in coordinating rice and fish growth. Guo et al. (2020) found in Qingtian, Zhejiang Province, that a rice spacing of 30 cm × 30 cm promoted fish growth while maintaining rice yield. Inayat et al. (2023) reported that higher rice planting density increased grain yield per unit area, whereas medium planting density was more favorable for balancing fish growth and rice production. Therefore, evaluations of rice production benefits under rice-fish coculture should comprehensively consider the actual cultivated area, yield components, and field infrastructure configuration, rather than assessing yield improvements solely on the basis of plant growth performance.

3.2 Pest, disease, and weed control

The control of pests, diseases, and weeds is an important mechanism through which rice-fish coculture improves rice production conditions. Certain fish species in paddy fields can feed on insects and other small aquatic organisms, while their swimming and foraging activities can interfere with weed establishment and growth. These activities reduce the abundance of some harmful organisms and alleviate competition between weeds and rice plants for nutrients and space. Through a four-year field experiment, Wan et al. (2019) found that, compared with rice monoculture, rice-fish coculture reduced the abundance of herbivorous insects by 24.07%, weed abundance by 67.62%, weed species richness by 62.01%, and weed biomass by 58.88%. Meanwhile, the abundance of invertebrate predators increased by 19.48%, and pesticide requirements decreased by 23.4%. A subsequent meta-analysis of 113 studies by Wan et al. (2026) further demonstrated that rice-fish coculture reduced herbivorous invertebrate pests by 24.1%, disease incidence by 38.8%, and weed abundance by 45.7%, while nearly doubling the abundance of natural enemies. These findings suggest that rice-fish coculture can control certain harmful organisms not only through direct fish predation but also by strengthening biological control through improvements in paddy field food-web structure.

The effects of rice-fish coculture on pest, disease, and weed control are selective and do not extend equally to all pests and diseases. In a five-year field study, Xie et al. (2011) found that rice-fish coculture reduced the occurrence of rice planthoppers, rice sheath blight, and certain weeds, but did not significantly suppress stem borers or rice leaf folders, which primarily damage the upper parts of rice plants. This difference may be related to pest habitat preferences and the feeding range of fish. Fish can knock some planthoppers into the water by colliding with rice stems, allowing the insects to be consumed, but they have limited direct access to pests inhabiting the upper leaves of rice plants. Jia et al. (2025) also found that koi effectively suppressed certain paddy field weeds, although their control of barnyardgrass established before fish stocking was relatively limited. Furthermore, rice-fish coculture can increase the abundance of predators and earthworms and improve soil conditions, thereby supporting rice production through multiple ecosystem services (Li et al., 2024). Therefore, rice-fish coculture should be integrated with pest and disease monitoring, appropriate planting density, and necessary environmentally friendly control measures to establish an integrated pest, disease, and weed management system based on ecological regulation.

3.3 Rice production stability and yield improvement

Rice production stability is an important indicator for evaluating the long-term application value of rice-fish coculture systems. Compared with yield in a single growing season, interannual yield fluctuations provide a more comprehensive indication of a production system's ability to adapt to environmental changes and biotic stress. By promoting nutrient cycling, maintaining ecological diversity, and suppressing certain pests, diseases, and weeds, rice-fish coculture can help reduce the dependence of rice production on external inputs. Through multiyear field surveys and experiments, Xie et al. (2011) found that average rice yields under rice-fish coculture and rice monoculture were generally comparable. However, rice-fish coculture maintained stable rice production while reducing pesticide and fertilizer inputs by 68% and 24%, respectively. Farmer-field surveys also indicated higher temporal yield stability under the coculture system. The study suggested that beneficial interactions between rice and fish could reduce the dependence of rice production on external chemical inputs through pest suppression and complementary nitrogen utilization. A survey covering 56 counties in China by Hu et al. (2016) further demonstrated that, when fish production remained below system-specific thresholds, rice-fish coculture could increase aquatic product output without reducing rice yield, while also decreasing nitrogen fertilizer and pesticide use. Therefore, the production advantages of rice-fish coculture are reflected not only in potential increases in grain yield but also in maintaining production stability under reduced chemical inputs and improving overall land-use efficiency.

The rice-fish coculture system in Qingtian, Zhejiang Province, is a representative traditional agricultural heritage system. Through multiyear farmer-field surveys and controlled experiments, Xie et al. (2011) found that rice-fish coculture could reduce pesticide and fertilizer inputs while maintaining rice yield. In particular, farmer-field surveys showed that the temporal stability of rice yield was higher under rice-fish coculture than under rice monoculture. The study further demonstrated that fish created favorable ecological conditions for rice production by feeding on certain pests, interfering with weed growth, and promoting complementary nitrogen utilization. This case illustrates that the value of rice-fish coculture extends beyond yield improvement in a single growing season and is also reflected in reduced external inputs, enhanced ecological regulation, and the maintenance of long-term production stability (Xie et al., 2011).

4 Economic Benefits of the Rice-Fish Coculture System

4.1 Combined production value of rice and fish

The rice-fish coculture system enables the simultaneous production of rice and aquatic products within the same paddy field, with its economic advantage primarily reflected in increased total production value per unit area. Compared with conventional rice monoculture, this system generates additional income from fish production while maintaining rice cultivation, thereby transforming paddy fields from single-crop production into diversified agricultural operations. The combined production value mainly consists of rice and fish output values and is jointly influenced by the yields and market prices of both products. Based on a global meta-analysis, Cui et al. (2023) found that the average total revenue of rice-animal coculture systems increased from US$1 681/ha under rice monoculture to US$ 3 815/ha, representing an increase of 127%, with additional aquatic animal products contributing substantially to revenue growth. A meta-analysis of integrated rice-fish farming systems in Africa also showed that rice-fish coculture increased total revenue by more than US$600/ha compared with rice monoculture, indicating that fish farming can effectively expand the sources of economic output from paddy fields (Goh et al., 2024). Therefore, the economic value of rice-fish coculture lies not only in increased fish production but also in improving the overall agricultural production value per unit area through the integrated utilization of the same land resources.

The combined production value varies among rice-fish coculture systems, mainly depending on fish species selection, stocking density, product market prices, and regional production conditions. Arunrat and Sereenonchai (2022) found that the average economic value of rice-fish coculture systems in Thailand was 25.40% higher than that of rice monoculture. Similarly, a study in Myanmar reported that the provisioning ecosystem service value of rice-fish coculture increased by 40.3%, reflecting not only the market value of rice and fish but also the value of products directly consumed by farming households (Myo et al., 2024). A household survey conducted by Berg et al. (2024) in the Mekong Delta, Vietnam, further revealed that fish income accounted for 18% and 39% of total income among rice-fish farmers with low and high fish stocking levels, respectively, indicating that fish production intensity can alter the composition of total farm income. In China, a four-year field experiment by Wan et al. (2019) found that the average economic value of rice-fish coculture was 10.33% higher than that of rice monoculture. These findings suggest that increasing aquatic product output at an appropriate level can improve total production value. However, the magnitude of additional income depends on local production conditions and market prices, and economic returns cannot be increased simply by expanding fish farming intensity.

4.2 Production costs and input structure

The production costs of rice-fish coculture systems mainly include rice cultivation inputs, fish farming inputs, and field infrastructure construction expenses. Rice cultivation costs involve seeds, fertilizers, pesticides, and mechanized field operations, while fish farming costs primarily include fingerlings, feed, and routine management. The construction of fish ditches, refuge ponds, escape-prevention facilities, and irrigation and drainage systems represents additional initial investment. Compared with rice monoculture, rice-fish coculture can utilize existing paddy fields for fish farming, but its production processes are more complex and require greater attention to infrastructure maintenance, labor allocation, and water-level management. A meta-analysis of integrated rice-fish farming systems in Africa by Goh et al. (2024) found that average production costs under rice-fish coculture were approximately US$300/ha higher than those under rice monoculture, mainly due to expenditures on fish ditch construction, fingerling purchases, feed, and protective facilities. Cui et al. (2023) also reported that total investment costs in rice-animal coculture systems were 142% higher than those in rice monoculture, although substantial differences existed among coculture types. Among these systems, rice-fish coculture had an average investment cost of US$843 ± 159/ha, lower than that of several other coculture systems, including rice-crayfish farming. Therefore, the cost advantages of rice-fish coculture do not necessarily involve simultaneous reductions in all production inputs. Instead, an appropriate balance must be established between additional aquaculture investments and the economic returns generated by integrated production.

In terms of cost structure, rice-fish coculture systems are characterized by simultaneous increases in certain expenditures and reductions in others. On the one hand, fingerling purchases, supplementary feed, aquaculture facility maintenance, and labor management increase production costs. On the other hand, fish can utilize natural food resources in paddy fields and reduce dependence on fertilizers and pesticides by promoting nutrient cycling and suppressing certain pests, diseases, and weeds. The meta-analysis by Cui et al. (2023) showed that mineral fertilizer and pesticide costs in rice-animal coculture systems decreased from US$262/ha under rice monoculture to US$187/ha, representing a reduction of approximately 29%. Goh et al. (2024) similarly indicated that rice-fish coculture could reduce some rice production costs by supplying nutrients through fish excreta and decreasing pesticide inputs. Household surveys in Indonesia also suggested that appropriately managed rice-fish coculture could reduce certain agricultural production inputs while increasing farmers' income (Mariyono, 2023). However, whether these cost savings translate into greater operational efficiency depends on production management practices. Samaddar et al. (2025) found that some rice-fish farmers obtained relatively low returns because of inefficient input management, insufficient funding, and a lack of technical training. Therefore, actual production cost assessments should also account for infrastructure depreciation, labor inputs, feed consumption, and aquaculture losses to avoid overestimating economic benefits by overlooking long-term expenditures.

4.3 Net returns and benefit-cost ratio

Net returns and the benefit-cost ratio are important indicators for evaluating the economic feasibility of rice-fish coculture systems. Net returns represent the actual earnings remaining after production costs are deducted from total production value, whereas the benefit-cost ratio measures the economic output generated per unit of production input. Although rice-fish coculture requires additional investment in fish farming and field infrastructure, revenue from aquatic products can offset these additional costs under suitable conditions, thereby improving overall profitability. A global meta-analysis by Cui et al. (2023) found that the average net returns of rice-animal coculture systems increased from US$1,019/ha under rice monoculture to US$2,212/ha, with the rice-fish coculture category showing an approximately 98% increase in net returns, indicating considerable potential for income improvement. Research conducted in Africa also found that although production costs under rice-fish coculture increased by approximately US$300/ha, total revenue rose by more than US$600/ha, resulting in an average net return increase of approximately US$300/ha (Figure 1) (Goh et al., 2024). Furthermore, a comparative study of different rice production systems in the Mekong Delta, Vietnam, by Berg et al. (2023) found that a system combining two rice crops with one fish crop achieved the highest annual net income and benefit-cost ratio among the production systems evaluated. These advantages were mainly attributable to lower agrochemical inputs and higher combined rice and fish production. These findings demonstrate that the economic advantages of rice-fish coculture depend not only on increased revenue but also on optimized input structures and effective production cost control.

The actual profitability of rice-fish coculture systems is also influenced by farming scale, fish market prices, management technologies, and environmental conditions. Berg et al. (2024) found that rice-fish farming households that effectively utilized the ecological functions of paddy fields and reduced pesticide and fertilizer inputs could achieve higher net income and benefit-cost ratios through lower production costs and greater combined rice and fish yields. The market value of cultured fish species also affects profitability. For example, experiments conducted in Arkansas, USA, estimated net returns of US$9,264/ha and US$7,442/ha from paddy-field koi farming in two experimental groups. However, the researchers emphasized that these results represented economic projections under specific experimental conditions and that a comprehensive economic feasibility assessment was still required (Jia et al., 2025). In contrast, a survey conducted by Samaddar et al. (2025) in Ziro Valley, India, found that inappropriate input management, insufficient funding, and inadequate technical training could result in relatively low economic returns from rice-fish coculture. In addition, extreme weather events, reduced fish survival rates, and fluctuations in market prices may further increase operational risks. Therefore, evaluations of the economic benefits of rice-fish coculture should adopt consistent accounting periods and per-unit-area standards, comprehensively assess total revenue, actual production costs, net returns, and benefit-cost ratios, and determine appropriate farming scales according to local environmental and market conditions to improve the stability and sustainability of economic returns.

5 Ecological and Resource Utilization Benefits of the Rice-Fish Coculture System

5.1 Nutrient cycling and fertilizer use efficiency

The rice-fish coculture system establishes a complementary nutrient cycling mechanism through material exchanges between rice plants and fish. Compared with conventional rice monoculture, fish excreta, uneaten feed, and other organic materials can release nutrients such as nitrogen and phosphorus through microbial decomposition, thereby supplying part of the nutritional requirements of rice plants and reducing dependence on external chemical fertilizers. Meanwhile, rice plants can absorb available nutrients from water and soil, reducing the accumulation of certain nutrients in paddy fields and improving nutrient recycling efficiency (Ge et al., 2023). Through long-term field surveys and experiments, Xie et al. (2011) found that traditional rice-fish coculture reduced chemical fertilizer use by 24% compared with rice monoculture, without a significant decline in rice yield. In a related nitrogen utilization experiment, approximately 31.8% of the nitrogen contained in rice grains and straw originated from fish feed, indicating that aquaculture inputs could contribute to rice growth through internal nutrient cycling. A global meta-analysis by Cui et al. (2023) further revealed that rice-animal coculture systems increased rice nitrogen use efficiency by an average of 6%, while reducing nitrogen fertilizer application by 30% and phosphorus and potassium fertilizer application by 22% and 19%, respectively. These findings demonstrate that rice-fish coculture and related integrated farming systems can reduce chemical inputs and improve resource utilization efficiency to some extent by promoting complementary nutrient utilization.

Nutrient cycling efficiency is also influenced by fish stocking density, feed inputs, fertilization practices, and field management conditions. Appropriate feeding can meet fish growth requirements while supplying nutrients to paddy fields through uneaten feed and fish excreta. However, excessive feeding may lead to nitrogen and phosphorus accumulation, increasing the risks of eutrophication and nutrient losses. Under conditions of equivalent total nitrogen inputs, Liu et al. (2024) found that replacing 50%-75% of basal fertilizer nitrogen with feed-derived nitrogen helped balance rice and fish production while reducing nutrient accumulation in fish ditch bottom soils. However, complete reliance on feed-derived nitrogen could reduce rice yield, indicating the importance of appropriately regulating nitrogen sources and their proportions. In an integrated ex-situ rice-fish coculture system, introducing aquaculture effluent into paddy fields for nutrient recovery reduced fertilizer use by 23.6% and promoted the enrichment of microbial communities involved in nitrogen and phosphorus transformation. A recent field study involving double-season rice production in southern China also found that rice-fish coculture increased soil available phosphorus by 9.52%-11.42%, nitrate nitrogen by 11.90%-12.82%, and rice yield by 3.25%-10.13%, demonstrating that appropriate crop-fish configurations can improve soil nutrient availability and support stable rice production (Liu et al., 2026). Therefore, fertilization and feed inputs should be coordinated according to fish growth requirements, rice nutrient uptake patterns, and soil fertility conditions to improve nutrient cycling efficiency in rice-fish coculture systems.

5.2 Agricultural non-point source pollution control and ecological environment improvement

The contribution of rice-fish coculture to agricultural non-point source pollution control is primarily reflected in reduced chemical inputs, enhanced nutrient transformation, and decreased nutrient losses. Excessive fertilizer and pesticide application in conventional rice production can increase nitrogen and phosphorus losses and the risk of aquatic environmental pollution. In contrast, rice-fish coculture can reduce certain fertilizer and pesticide inputs through fish predation on pests and weeds, utilization of natural food resources, and enhanced nutrient cycling. Through field surveys, Xie et al. (2011) found that traditional rice-fish coculture reduced pesticide and fertilizer use by 68% and 24%, respectively, compared with rice monoculture, indicating its potential to decrease agricultural chemical inputs. A global meta-analysis by Cui et al. (2023) demonstrated that rice-animal coculture systems reduced nitrogen losses through surface runoff and leaching by 16% and 13%, respectively, while increasing nitrogen retention in soil and rice plants (Figure 2). In an integrated ex-situ rice-fish coculture system, Liu et al. (2023) found that treatment of aquaculture effluent in paddy fields reduced total nitrogen, total phosphorus, and the permanganate index by 72.78%, 63.81%, and 53.32%, respectively, while concentrations of ammonia nitrogen, nitrite nitrogen, and dissolved inorganic phosphorus also decreased substantially. Similarly, Feng et al. (2016) reported that several nitrogen and phosphorus indicators in the water were significantly lower in a pond-based rice-fish coculture system than in fish monoculture ponds. These findings indicate that appropriately designed rice-fish coculture systems can not only reduce pollutant generation but also improve aquaculture water quality through nutrient uptake and transformation by rice plants and associated microorganisms.

Rice-fish coculture can also positively influence the ecological environment by altering paddy field food-web structure and biological community composition. Fish predation on certain herbivorous insects and weeds helps maintain the relative balance of biological communities in paddy fields while reducing the effects of chemical pest control on non-target organisms. Through a comprehensive analysis, Ge et al. (2023) indicated that rice-animal coculture systems could support soil fertility maintenance and biodiversity conservation through biological interactions, complementary nutrient utilization, and microbially mediated elemental cycling. A study of the integrated rice-fish farming system in the Hani Terraces of Yunnan Province by Li et al. (2021) also demonstrated that traditional coculture practices play a role in maintaining paddy field biodiversity and ecosystem stability. However, rice-fish coculture does not necessarily improve all environmental indicators. The meta-analysis by Cui et al. (2023) found that although rice-animal coculture systems reduced overall methane emissions by an average of 11%, methane emissions from the rice-fish coculture category increased by an average of 29%, indicating substantial differences in greenhouse gas emission responses among coculture types. These differences may be associated with changes in paddy water management, soil redox conditions, and organic matter decomposition processes. Therefore, evaluations of the ecological benefits of rice-fish coculture should simultaneously consider agricultural chemical inputs, nutrient losses, water quality changes, biodiversity, and greenhouse gas emissions, rather than assessing ecological advantages solely on the basis of individual environmental indicators.

5.3 Land and water resource utilization efficiency

Integrated land use is an important advantage of the rice-fish coculture system. By simultaneously producing rice and fish within the same paddy field, this system makes full use of aquatic space and the ecological niches of different organisms, thereby enabling the integrated utilization of agricultural production space. Compared with rice monoculture, rice-fish coculture can increase aquatic product output without requiring the construction of separate, full-scale aquaculture ponds, thereby improving overall production capacity per unit land area. A global meta-analysis by Cui et al. (2023) found that rice-animal coculture systems increased rice yield by an average of 4% and reduced the need for additional agricultural land through the combined production of grain and aquatic products. A systematic review by Fernandez-Zatrate et al. (2025) also indicated that rice-fish coculture enables the simultaneous production of rice and fish on the same land area, demonstrating its potential to improve agricultural land-use efficiency. In flood-prone lowland areas of eastern India, Rautaray et al. (2025) integrated land modification with crop-fish farming and found that land productivity and net returns were 3.8 and 2.2 times those of a conventional rainfed rice-fallow system, respectively. These findings suggest that appropriate field layouts and water resource management can improve the overall productive capacity of lowland agricultural areas. However, excessive land occupation by fish ditches, refuge ponds, and other aquaculture facilities may reduce the effective rice cultivation area. Therefore, improvements in land-use efficiency must be based on an appropriate spatial allocation between rice cultivation and fish farming.

Regarding water resource utilization, rice-fish coculture allows the same water body to support both rice cultivation and fish farming, thereby increasing overall output per unit of water used. Based on a synthesis of previous studies, Ahmed et al. (2022) reported that the economic water productivity of rice-fish coculture was approximately US$0.41/m³, substantially higher than the US$0.19/m³ recorded for rice monoculture, indicating that additional fish production can increase the economic value generated from agricultural water use. Nevertheless, rice cultivation and fish farming have different requirements for water depth, water quality, and irrigation conditions, and certain production practices may increase supplementary water requirements and water losses. Therefore, improving water-use efficiency requires coordinated management of irrigation and aquaculture water. In an integrated ex-situ rice-fish coculture system, Liu et al. (2023) found that water consumption was reduced by 47.5% compared with rice monoculture, indicating that recycling aquaculture effluent could reduce dependence on external water supplies. A floating-bed rice-fish coculture study by Goda et al. (2023) also demonstrated that integrating rice cultivation with pond aquaculture could improve water-use efficiency and nitrogen and phosphorus utilization. Furthermore, Rautaray et al. (2025) found that the economic water productivity of an integrated crop-fish farming system was 2.1 times that of the control system. Overall, the water-saving potential of rice-fish coculture is jointly influenced by regional rainfall, field hydrological conditions, infrastructure design, and management practices. Appropriate water-level regulation, improved irrigation and drainage facilities, and enhanced aquaculture water recycling should therefore be implemented to reduce unnecessary water consumption while maintaining favorable conditions for rice and fish growth.

6 Effects of the Rice-Fish Coculture System on Product Quality and Overall Production Value

6.1 Fish nutritional quality

The rice-fish coculture system not only affects fish growth performance and aquaculture yield but also influences the nutritional composition and edible quality of fish muscle by altering natural food sources, aquatic environmental conditions, and fish metabolic activities. Compared with conventional pond aquaculture, paddy fields are characterized by diverse food resources and complex ecological conditions, which may influence the accumulation of proteins, lipids, amino acids, and fatty acids in fish muscle. He et al. (2020) compared the muscle quality of tilapia under rice-fish coculture and monoculture conditions and found that fish reared in the coculture system exhibited higher muscle protein content, lower lipid content, and improved free amino acid composition. The concentrations of adenosine monophosphate (AMP) and inosine monophosphate (IMP) also increased, accompanied by more pronounced umami and sweet flavors and reduced earthy and musty odors. Similarly, Zhou et al. (2024) compared Opsariichthys bidens cultured in rice fields and conventional ponds and found that fish from rice fields had higher muscle protein content, lower lipid content, and a greater diversity of flavor compounds. The combined contents of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were also higher than those in pond-cultured fish, whereas no significant differences were observed in amino acid composition between the two groups. These findings indicate that rice-fish coculture can improve certain aspects of fish nutritional quality and flavor, although the responses of individual nutritional indicators are not entirely consistent.

The quality responses of different fish species to paddy field aquaculture conditions are also influenced by species-specific characteristics and management practices. Fan et al. (2026) compared the quality characteristics of Acrossocheilus fasciatus under four aquaculture systems and found that rice field-cultured fish exhibited the highest contents of umami-related amino acids and significantly increased levels of polyunsaturated fatty acids (PUFAs), particularly EPA and DHA, together with improved muscle texture and flavor characteristics. Inayat et al. (2023) found that medium rice planting density contributed to improved muscle quality in tilapia and common carp. Under the same culture conditions, tilapia exhibited higher concentrations of certain nutritional components than common carp. Furthermore, Zhou et al. (2026) investigated the nutritional characteristics of yellow catfish (Pelteobagrus fulvidraco) and found that rice field-cultured fish had higher muscle contents of serine, valine, isoleucine, and total essential amino acids, whereas pond-cultured fish exhibited higher total fatty acid content and greater accumulation of certain lipid metabolism-related compounds. These findings further demonstrate that rice field aquaculture does not necessarily improve all nutritional indicators simultaneously. Therefore, evaluations of fish quality in rice-fish coculture systems should comprehensively consider species-specific characteristics, protein content, essential amino acid composition, fatty acid profiles, and flavor compounds, rather than assuming that ecological aquaculture universally improves all aspects of nutritional quality.

6.2 Rice grain quality

The rice-fish coculture system can influence rice milling quality, appearance quality, and eating quality by regulating nutrient cycling, soil conditions, and nutrient availability in paddy fields. Fish excreta and other organic residues can release nutrients through microbial decomposition, thereby influencing grain formation and the accumulation of nutritional compounds. Based on a meta-analysis of 456 paired observations from 129 field studies, Li et al. (2022) found that the coculture of rice with aquatic animals generally improved rice yield and grain quality, with rice-fish coculture showing considerable application potential. However, the magnitude of these improvements depended on coculture type, regional environmental conditions, and fertilization practices. Through a four-year field experiment, Wan et al. (2019) found that rice-fish coculture improved rice grain quality while enhancing soil conditions. Xu et al. (2025) further investigated soil properties and grain quality under different integrated rice-based farming systems and found that the protein contents of rice grains under rice-fish and rice-chicken-fish coculture were 8.21% and 8.20%, respectively, representing an increase of approximately 16.6% compared with the 7.04% recorded under conventional rice monoculture. Meanwhile, grain chalkiness decreased by approximately 20%-30% under different coculture treatments. These changes were associated with soil nutrient conditions, enzyme activities, and microbial community composition, indicating that rice-fish coculture can improve certain grain quality attributes by enhancing the paddy field ecological environment.

The effects of rice-fish coculture on grain quality are also associated with rice varieties, fish stocking density, and field management practices. Li et al. (2023) comprehensively evaluated the yield, lodging resistance, and grain quality of 33 rice varieties in a rice-common carp coculture system and found substantial differences among varieties in brown rice recovery, milled rice recovery, head rice recovery, protein content, and chalkiness, indicating that varietal selection is an important factor influencing rice grain quality. Wang et al. (2023) conducted a three-season experiment using the aromatic rice variety Meixiangzhan 2 and found that rice-fish coculture increased the content of 2-acetyl-1-pyrroline (2-AP), a major aroma compound in rice grains, by 2.5%-49.4%. The coculture system also improved the seed-setting rate and head rice recovery while reducing grain chalkiness. Among the treatments, a fish stocking density of 15,000 fish/ha produced relatively favorable overall results, while rice yield did not differ significantly among treatments. These findings suggest that appropriate rice variety selection and fish stocking density can improve certain milling, nutritional, and eating quality attributes while maintaining grain yield. Nevertheless, suitable crop-fish configurations should be determined according to varietal characteristics and specific production conditions.

6.3 Added value of ecological products

Rice and fish produced through rice-fish coculture possess characteristics associated with both agricultural production and ecological farming, creating opportunities for product differentiation and increased overall production value. In addition to the nutritional quality and market value of agricultural products, this system can generate ecosystem service value through nutrient cycling, environmental regulation, and the conservation of traditional agricultural culture. Through field experiments comparing different rice production systems, Ye et al. (2024) found that the total ecosystem service value of rice-fish coculture reached approximately US$43,700/(ha·year), representing a 14.4% increase compared with rice monoculture, while the provisioning value of major agricultural products increased by 63%. Arunrat and Sereenonchai (2022) also found that the average economic value of rice-fish coculture systems in Thailand was 25.40% higher than that of rice monoculture, with benefits derived from rice and fish products as well as multiple ecosystem services. In Myanmar, Myo et al. (2024) reported that the agricultural provisioning service value of rice-fish coculture was 40.3% higher than that of rice monoculture. Some of these products were also consumed directly by farming households, contributing to household food availability and economic security. It should be noted that ecosystem service value includes estimated values of non-market ecological functions and therefore cannot be directly equated with farmers' actual sales revenue. Accordingly, assessments of the overall production value of rice-fish coculture should distinguish between agricultural market returns and ecosystem service contributions to avoid double counting.

Realizing the added value of ecological products also depends on standardized production, product certification, processing, distribution, and brand development. Compared with conventional agricultural products, rice-fish coculture products can enhance consumer confidence in product quality and production practices through quality testing, green or organic certification, traceability systems, and branding associated with agricultural heritage. Li et al. (2026) investigated the rice-fish coculture system in Qingtian, Zhejiang Province, and found that locally certified rice produced under the coculture system was sold for approximately CNY 8/kg, compared with approximately CNY 6/kg for uncertified products, indicating that product certification has the potential to generate a market price premium. The study further suggested that the market recognition of Qingtian rice-fish products could be improved through primary processing, packaging and labeling, and both online and offline marketing, while agricultural heritage resources could support the development and promotion of specialty products. However, certification, processing, and distribution also involve additional costs, and some farmers continue to face challenges associated with small production scales, limited processing capacity, and insufficient market access. Therefore, the added value of rice-fish coculture products cannot be achieved solely by promoting the concept of ecological farming. Instead, stable product quality, standardized production practices, credible certification and labeling, and effective cost control are essential for transforming ecological advantages and cultural characteristics into sustainable market competitiveness.

7 Major Constraints and Optimization Strategies for Improving the Benefits of Rice-Fish Coculture Systems

7.1 Optimization of fish species selection and stocking density

Fish species selection and stocking density are important factors influencing the production benefits of rice-fish coculture systems. Different fish species vary in environmental adaptability, feeding habits, growth rates, and market value, resulting in differences in their utilization of aquatic space and natural food resources in paddy fields. Commonly cultured species, such as common carp, crucian carp, and tilapia, exhibit a certain degree of adaptability to paddy field environments, although their requirements for water temperature, dissolved oxygen, and available space differ. Ji et al. (2023) indicated that biological compatibility between rice plants and aquatic animals is an important foundation for establishing stable ecological interactions, and that appropriate combinations of rice varieties and fish species can improve overall production benefits. A systematic review by Fernandez-Zatrate et al. (2025) further revealed that existing rice-fish coculture studies have mainly focused on common carp and tilapia, accounting for 37% and 29% of the fish species records included in the review, respectively, whereas research on other potentially suitable species remains relatively limited. Zhu et al. (2024) also highlighted substantial regional differences in paddy field conditions, fish species configurations, and production management practices, indicating a lack of universally applicable aquaculture strategies across different regions. Therefore, fish species selection should comprehensively consider regional climate, water availability, culture duration, and market demand. Priority should be given to species that are well adapted to local shallow-water environments, exhibit strong stress tolerance, efficiently utilize natural food resources, and have stable market value. Appropriate crop-fish combinations should also be identified through regional adaptability trials.

Stocking density directly affects fish growth performance, feed utilization, survival rate, and rice production. Insufficient stocking density may lead to underutilization of aquaculture space and natural food resources in paddy fields, whereas excessive density can intensify competition for food and space, increasing the risks of water quality deterioration and aquaculture losses. Fernandez-Zatrate et al. (2025) reported an average stocking density of approximately 13,390 fish/ha across the rice-fish coculture studies included in their review, with fish generally stocked approximately 27 days after rice planting. However, substantial differences were observed among fish species and culture practices. Wang et al. (2023) evaluated three stocking densities of 9,000, 15,000, and 21,000 fish/ha in an aromatic rice-fish coculture experiment and found that the treatment with 15,000 fish/ha produced relatively favorable improvements in rice aroma and certain grain quality attributes without significantly reducing rice yield. Guo et al. (2020) also found in Qingtian, Zhejiang Province, that a rice planting spacing of 30 cm × 30 cm supported better fish growth while maintaining rice yield, suggesting that rice planting density and fish stocking density should be optimized in a coordinated manner. Nevertheless, these findings were obtained under specific experimental conditions and cannot be regarded as universal production standards for all rice-fish coculture systems. Therefore, combined trials involving different stocking densities and rice planting arrangements should be conducted, with fish growth, survival rate, rice yield, water quality changes, and economic returns considered simultaneously. Appropriate production configurations should be determined within the environmental carrying capacity of paddy fields (Inayat et al., 2023; Zhu et al., 2024).

7.2 Optimization of paddy field environmental regulation and aquaculture management

Dynamic changes in paddy field conditions are important constraints on the stable production of rice-fish coculture systems. Because paddy fields generally have relatively shallow water, water temperature, dissolved oxygen, pH, and water levels are readily affected by weather conditions, irrigation management, and rice growth. Extreme heat, prolonged drought, and heavy rainfall may further increase aquaculture risks. Ahmed et al. (2022) identified water resource management as an important factor limiting the adoption of rice-fish coculture, particularly in regions with inadequate irrigation infrastructure, difficulty maintaining appropriate water depths, and insufficient drainage facilities, where fish survival and system stability are more vulnerable to environmental fluctuations. A systematic review by Zhu et al. (2024) also indicated that field environmental conditions and routine management practices are important determinants of production performance in integrated rice-aquaculture systems. In addition, poorly designed fish ditches and refuge ponds, or excessive land occupation by refuge facilities, may reduce the effective rice cultivation area and compromise the combined production benefits of rice and fish. Hu et al. (2016) found that intensive rice-fish coculture systems could maintain rice yield when fish production remained below system-specific thresholds, whereas excessive aquaculture intensification could result in reduced rice yield. Therefore, fish refuge areas and irrigation and drainage facilities should be appropriately designed according to rice growth stages and fish requirements. Field bunds and escape-prevention measures should also be improved, while monitoring of water temperature, dissolved oxygen, pH, and water levels should be strengthened. The gradual adoption of appropriate environmental monitoring and precision regulation technologies could further improve the stability of paddy field aquaculture environments.

Scientific feeding practices, nutrient management, and environmentally friendly pest and disease control are also essential for improving the overall benefits of rice-fish coculture. Natural food resources in paddy fields can meet part of the nutritional requirements of cultured fish, but their availability varies with season and rice growth stage. Excessive feeding and fertilization may lead to nutrient accumulation, increasing aquaculture costs and the risk of eutrophication. Samaddar et al. (2026) conducted a study in Ziro Valley, India, and found that rice-fish coculture treatments receiving only irrigation water exhibited relatively favorable production and ecological performance. In contrast, the addition of domestic and livestock wastewater increased ammonia concentrations and caused a certain degree of eutrophication stress, indicating that greater nutrient inputs do not necessarily improve production benefits. Therefore, supplementary feeding rates should be adjusted according to fish size, growth rate, and natural food availability, while fertilizer inputs should be controlled in accordance with rice nutrient requirements to prevent excessive nutrient enrichment. Regarding pest and disease management, rice-fish coculture can suppress certain pests and weeds through fish feeding activities and food-web interactions, but these ecological functions should be complemented by field monitoring, agronomic control measures, and other environmentally friendly management practices (Ji et al., 2023). When chemical treatments are necessary, inputs should comply with relevant regulations and be suitable for integrated rice-aquaculture systems. Application requirements and prescribed safety intervals should be strictly followed, while monitoring of fish diseases and parasites should be strengthened. By coordinating water management, nutrient inputs, fish biomass, and agricultural chemical use, rice-fish coculture systems can maintain stable paddy field ecosystems while supporting normal fish growth.

7.3 Standardized production and industrial development

The wider adoption of rice-fish coculture systems remains constrained by inconsistent production technologies, differences in management capacity, insufficient financial investment, and fragmented farming operations. Considerable regional variations exist in paddy field infrastructure, fish species selection, stocking density, and rice cultivation practices, while the absence of standardized management may lead to fluctuations in production efficiency and economic returns. Through a survey of farmers in Ziro Valley, India, Samaddar et al. (2025) found that inefficient input management, limited financial resources, and insufficient formal technical training were important factors contributing to relatively low economic returns among some rice-fish farmers. To address these challenges, China has issued the national standard General Technical Requirements for Integrated Rice-Aquaculture Farming (GB/T 43508-2023), providing technical guidance for standardized integrated rice-aquaculture production. The Ministry of Agriculture and Rural Affairs of China (2025) further emphasized the implementation of national standards, strengthened management of the proportion of land occupied by ditches and ponds, rice yield per unit area, agricultural input use, and product quality and safety, as well as technological innovation involving production techniques, varieties, and equipment. Therefore, standardized technical systems should be established according to regional production characteristics, covering fingerling selection, paddy field infrastructure, appropriate stocking practices, feed management, water quality monitoring, agricultural input management, and product quality testing. Meanwhile, demonstration projects, technical training, and production record management should be strengthened to improve farmers' capacity for standardized production.

Industrial development is an important pathway for transforming rice-fish coculture from fragmented farming operations into a production system capable of generating stable income. Currently, some regions continue to face challenges associated with small-scale farming entities, limited organizational capacity, inadequate processing facilities, and restricted marketing channels, which constrain the realization of added value from ecological products. Yuan et al. (2022) indicated that advances in ecological research, aquaculture technological innovation, and policy support are important drivers of the development of integrated rice-aquaculture systems in China. Coordinated improvements in production technologies and industrial organization can help enhance resource utilization and operational efficiency. The Ministry of Agriculture and Rural Affairs of China (2025) also proposed promoting coordinated development in standardized cultivation and aquaculture, intensive processing, integrated logistics, brand-oriented marketing, and comprehensive agricultural services throughout the production chain. Accordingly, cooperation among farmers' cooperatives, family farms, and agricultural enterprises should be strengthened to facilitate effective coordination among fingerling supply, production management, product processing, and marketing, while improving product traceability and regional brand development. Li et al. (2026), in their study of the Qingtian Rice-Fish Culture System in Zhejiang Province, further demonstrated that ecological agricultural certification, primary processing, packaging and labeling, and online and offline marketing could contribute to product value enhancement, while agricultural heritage resources could support the development of specialty products. For emerging production regions such as the southern United States, Jia et al. (2025) suggested that rice-fish coculture has potential for agricultural diversification, although further improvements in production infrastructure and comprehensive economic feasibility assessments are still required. Therefore, the industrial development of rice-fish coculture systems should integrate locally adapted practices, standardized production, and coordinated value-chain development to improve operational stability and market competitiveness while maintaining stable rice production and ecological functions.

8 Conclusion and Prospects

Rice-fish coculture is an integrated agricultural production system that combines rice cultivation and fish farming within the same paddy field, offering considerable potential for improving agricultural productivity and resource utilization. Through ecological interactions between rice plants and fish, this system can promote nutrient cycling, enhance the utilization of natural food resources, and reduce the dependence on certain agricultural chemical inputs. Fish production provides an additional source of agricultural output and income, while rice cultivation contributes to maintaining a suitable ecological environment for aquatic organisms. However, fish growth, survival, and yield vary considerably with species selection, stocking density, rice planting arrangements, and environmental conditions. Therefore, the production advantages of rice-fish coculture should be evaluated in terms of the coordinated performance of rice and fish rather than the maximization of either component alone.

Rice-fish coculture also demonstrates potential economic and ecological benefits. The combined production of rice and fish can increase total output value and net returns per unit area, while nutrient recycling and biological pest control may reduce fertilizer and pesticide requirements. In addition, appropriate coculture practices can improve certain nutritional and sensory characteristics of fish and rice, creating opportunities for product differentiation and market value enhancement. Nevertheless, these benefits are not consistent across all production systems. Additional investments in fish fingerlings, feed, infrastructure, and labor may increase production costs, while excessive stocking density and nutrient inputs can lead to water quality deterioration and reduced production efficiency. Furthermore, improvements in nutrient utilization and reduced chemical inputs do not necessarily result in lower greenhouse gas emissions under all conditions. Consequently, comprehensive evaluations should consider production performance, economic returns, product quality, resource utilization, and environmental impacts simultaneously.

The sustainable development of rice-fish coculture remains constrained by regional differences in climate, water availability, farming infrastructure, technical capacity, and market conditions. Optimizing fish species selection and stocking density, improving paddy field infrastructure, and strengthening water quality monitoring and nutrient management are essential for maintaining stable production. Meanwhile, standardized farming practices, technical training, product quality control, and coordinated value-chain development can help improve management efficiency and market competitiveness. Future research should emphasize long-term, multi-location field experiments to clarify the interactions among fish growth, rice yield stability, nutrient cycling, and environmental impacts. Greater attention should also be given to species-specific adaptation, appropriate stocking strategies, resource-use efficiency, and the economic feasibility of different coculture configurations.

Rice-fish coculture offers a promising pathway for integrating grain production, aquaculture, and ecological management. Its long-term value lies not simply in increasing agricultural output but in achieving a more balanced relationship among production efficiency, economic profitability, product quality, and environmental sustainability. By combining locally adapted management strategies with technological innovation, standardized production, and effective market organization, rice-fish coculture systems can contribute to the sustainable intensification of rice-based agriculture and support the transition toward more resource-efficient and environmentally sustainable food production.

Conflict of Interest Disclosure

The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

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