Abstract Ricefish integrated farming （RFIF） can change the agricultural production pattern from monofarming model to the cofarming model， and the stereoscopic and integrated farming system established by RFIF can change the flat production to the stereoscopic production. Therefore， RFIF is the important development direction for agriculture to change pattern and adjust structure. In order to further promote development of the research and application of RFIF， the general development situation of RFIF in China was reviewed； the effects of RFIF on increasing farmer income and enhancing agricultural efficiency were clarified. The technologies matched with RFIF， such as rice paddy engineering technology， safe plant protection technology， security fertilization technology， fish disease prevention and control technology and water quality management technology， were summarized， and the supporting role of RFIF for agriculture was pointed out. In addition， the development prospect of RFIF was proposed， as well as the key research direction of RFIF.
　　Key words Rice； Fishery； Integrated farming； Development situation
　　China is a big country in fishery production， and fisheries play an increasingly prominent role in the development of the national economy in China. In particular， since the reform and opening up， fisheries have become an important part of ensuring national food security. After the 1990s， intensive pond aquaculture featured with artificial enhancement has been rapidly developed and played an important role in improving the supply of aquatic products and ensuring food safety. However， the intensive aquaculture practices with high density， high feed rate， and high water exchange rate not only cause environmental pressure on the ponds themselves， but also reduce the quality of the aquaculture products. Moreover， the aquaculture drainage also aggravates the environmental load of surrounding water bodies， causing peoples concerns on whether it can achieve sustainable development[1]. Moreover， generally only 20-30% of the nitrogen and phosphorusbased nutrients that are used in intensive aquaculture production can be absorbed by fish growth. Numerous nutrients exist in water and sediment in various forms. After the aquaculture process has occupied and discharged surface water resources， the eutrophication materials in the water have increased significantly， and the pollutants such as ammonia nitrogen and COD have also increased significantly. The discharge of aquaculture wastewater has increased the load on natural waters， causing negative impacts and becoming a major nonpoint source pollution. At present， promoting the adjustment and upgrading of the agricultural industry structure goes parallel with the integration of industrial convergence. Therefore， changing production methods， improving the ecological environment， and increasing resource utilization are becoming new challenges for fishery production. 　　In accordance with the requirements of sustainable development， changing aquaculture production methods must consider both increasing the efficiency of aquaculture water use and achieving watersaving and emission reduction of aquaculture systems. In the future， aquaculture must focus on sustainable development. While increasing production， quality must be ensured， and attention must be paid to environmental protection. Therefore， research and development of highyield， productsafety， resourcesaving， environmentfriendly aquatic aquaculture technology and aquaculture models have become an important direction for fishery production at home and abroad. The ricefish integrated farming （RFIF） can change the agricultural production pattern from monofarming model to the cofarming model， and the stereoscopic and integrated farming system established by RFIF can change the flat production to the stereoscopic production. Thus， it is considered to be a kind of industry model which can achieve grain stabilization， fishing promotion， income increase， quality improvement， environmental friendly and sustainable development[2-4]. Therefore， it is bound to be an important development direction for the agricultural industry to transfer mode and adjust structure.
　　Overview of RiceFish Integrated Farming in China
　　Ricefish integrated farming （RFIF） is a kind of compound agricultural production method that integrates rice cultivation and aquaculture. Ecologically speaking， it is a ricefish （shrimp， crab， etc.） symbiosis ecosystem led by rice and fish （shrimp， crab， etc.） formed after the introduction of fish （shrimp， crab， etc.） populations in paddy field ecosystems. China has a long history of the integrated farming of rice and fish. However， it was not until the late 1970s that the RFIF had developed into a fishery industry. Afterwards， the development of RFIF has gone through 5 periods， which are the initial development period （1978-1985）， the productive development period （1986-1992）， the extended development period （1993-2002）， the integrated development period （2003-2012） and a new era of comprehensive innovative development （since 2013）. During the development periods of RFIF， although the area have ups and falls， the fishery yield has been on the rise （Fig. 1）.
　　1978-1985 was a period of initial development for RFIF. In 1983， the 1st National Rice Field Fish （Crab） Farming Experience Exchange Conference organized by the Ministry of Agriculture， Animal Husbandry and Fisheries at that time was held in Chengdu， Sichuan Province. This meeting defined some basic policies for RFIF， which promoted the rapid development of RFIF. The rapid development of RFIF led to many new breakthroughs， which not only revolutionized the traditional RFIF technology， innovated RFIF model， but also greatly increased the fish farming species. Bream， chub， crucian， grass carp and other bulk freshwater fish species were added to the original carpbased fish farming， so that RFIF started the initial development， and in 1985 the area of RFIF reached 648.67×103 hm2. 　　1986-1992 was the period of productive development of RFIF. In 1990， the 2nd National Rice Field Fish （Crab） Farming Experience Exchange Conference organized by the Ministry of Agriculture was held in Chongqing， which promoted the development of RFIF from experimental to productive， extensive to intensive. Therefore， the industrial base for RFIF was laid， and the productive development period of RFIF began. By 1992， the area of RFIF reached up to 782.61 × 103 hm2.
　　1993-2002 was the extended development period for RFIF， when the fish species for RFIF expanded from the bulk freshwater fish to snakeheaded fish， channel catfish， finless eel， oysters， turtles， shrimps， crabs and other specialty fish and frogs. In 1994， the 3rd National Rice Field Fish （Crab） Farming Experience Exchange Conference organized by the Ministry of Agriculture was held in Panjin City， Liaoning Province， marking RFIF developed from the mono ricefish farming to the diversified farming like ricefish， riceshrimp， ricecrab， ricefrog， from traditional farming to engineering farming. The industrial extension of RFIF was expanded， making the beginning of extended development period of RFIF. In 2002， the area of RFIF reached 1 618.24×103 hm2， which was the largest in history.
　　2003-2012 was a period of integrated development of RFIF. With the continuous adjustment and upgrading of agricultural industrial structure in China， RFIF also evolved into the integrated development of fisheryanimal husbandry， fisheryagriculture， fisheryindustry and trade， creating many integrated production modes like fishfruit， fishmulberry， fishflowers， fishcane， fishvegetables， fishgrass， fishducks， fishpigs. Thus， the integrated farming initially formed its regional layout， specialized production， largescale development， and industrialized management， and the industry integration of RFIF was further deepened， achieving the integrated development. During this period， the area of RFIF showed some decrease， and in 2012， the area was reduced to 1 294.92×103 hm2.
　　Since 2013， in the process of transferring mode and adjusting structure of agriculture， RFIF has received high attention as an efficient， resourcesaving， environmentfriendly ecoagriculture and green agricultural production method[15-17]. Under the vigorous promotion and guidance of the Ministry of Agriculture and local governments at all levels and under the active exploration and practice of scientific and technical personnel and farmers， a new wave of RFIF development boom has been stirred up across China， forming the RFIF mode which is centered on rice， led by characteristic aquatic products， characterized by industrialized management， largescale development， and standardized production， thereby achieving the goal of "promoting rice with fish， stabilizing grain efficiency， quality and safety， and ecological protection". At present， RFIF has formed 19 typical patterns of 5 categories of ricefish， riceshrimp， ricecrab， riceturtle， riceloach[18-19]. The area for RFIF also rose significantly. The areas in 2013 and 2015 reached 1 520.69×103 hm2 and 1 501.63×103 hm2， respectively， which almost reached the highest level in history. On October 18， 2016， the China Strategic Alliance for RiceFish Integrated Farming Innovation was set up， marking a new era of comprehensive innovation and development for RFIF. 　　Research Status of RFIF Techniques
　　Research on RFIF techniques
　　Research on increasing production and increasing efficiency The research on increasing production and increasing efficiency of RFIF is currently focused on the effects of fish （shrimp， crab） on rice and rice fields， including disease control， pest management， weed control， fertilizer application， as well as the effect on rice quality and rice yield. Centered on these themes， domestic and foreign scholars have conducted a series of research and exploration， but the research conclusions are still different. Nepalese scholars believe that compared with rice， rice yield in rice paddy fields would increase significantly[20]； Bangladeshi scholars[21]also found the yieldincreasing effects when raising shrimps in paddy fields in studying shrimprice integrated farming mode. In addition， some studies in China have also shown that the integrated farming of rice and fish can increase the yield and enhance the efficiency， and the yield increase of rice per unit area could reach as much as 5%-15%[22]. The fishes in paddy fields can effectively control the pests and weeds in the fields[23-24]， and excrement such as fish manure can provide nutrients for rice， thus promoting rice production. On the other hands， the weeds and pests in rice fields can provide food for fishes， while the growth of rice purifies the water， which promotes the yield increase of fishes[25]. Therefore， in the compound ecosystem of ricefish farming， matters are undergoing a benign cycle in the fields， and the energy flows toward the direction beneficial both to rice and fishes （shrimp and crab）， forming a mutually beneficial symbiosis ecosystem of rice and fishes， thus achieving the goals of dual uses of water， double harvests of fields， grain stabilization and efficiency increase， winwin food and fishery. However， unlike the above findings， Berg et al.[26]found no significant increase in rice yield when studying the fishrice farming in the Mekong Delta； previously， Rothuis et al.[27]also concluded the same results in the ricefish farming tests conducted the shallow water area of the Mekong River. In addition， similar conclusions were obtained in the study of the effects of the integrated farming of 4 different fishes on rice yield conducted by Vromant et al.[28]and the study on the ricecrab integrated farming conducted by Chinese scholars[29-30].
　　The different research results for the same farming mode may be due to differences in the types of aquatic organisms， rice varieties， and applied fertilizers[31]； moreover， the differences in the climate， field management methods， and water quality of different places are also important factors that cause different research results[32]. Therefore， in the RFIF ecosystem， rice varieties， fish species， stocking time， individual size， and management methods must be suitable and appropriate to achieve the full complementary interaction between fishes and rice， promote the virtuous circulation of matters in the RFIF ecosystem， and energy flowing in favor of rice and fish[25]. 　　Paddy field engineering techniques The paddy field engineering techniques mainly include field ridge preparation technique， fish pit and fish ditch excavation technique， water inlet and outlet setting technique， and antiescaping technique. In terms of field ridge preparation technique， the ridges should be repaired， reinforced， and compacted before releasing the fishes， so that the field ridges do not seep or leak water[33-34]. In terms of fish pit and fish ditch excavation technique， it is suggested that the number of fish pit in the ricefish farming fields should be determined by the size of the rice paddies， and it should be located in the corner or at the middle of the entrance of the water intake in the shape of rectangular， circular or triangular. The 4 walls of fish pit should be protected using stone bands， bricks or other hard materials and cement in fixed locations， and the pits and ditches should be connected with each other[35]. At present， the common shapes of fish pits include the shapes of the Chinese characters of "一" （yi）， "十" （shi）， "艸" （ao）， "井" （jing）， "田" （tian）， "目"（mu）， "囲" （wei）， and the specific shape is determined according to the area of the paddy field[36-38]. The paddy field with the area of less than 0.3 hm2 is in the shape of Chinese character "十" or "井"， while the paddy field with the area over 0.3 hm2 in the shape of Chinese character "井" or "目"， "囲". The water inlet and outlet for RFIF are usually set on the ridges on the opposite corners of the paddy field[39]. The culverts are made of or buried with bricks， stones， the width of which is determined by the size of the field. Generally， 1-3 spillways are set on the field ridge at the outlet side to control the water level.
　　Antiescaping is an important part of rice field engineering techniques， and specific antiescaping techniques have been developed corresponding to the 5 RFIF modes of ricefish farming， ricecrab farming， riceshrimp farming， riceturtle farming， riceloach farming. The antiescaping technique for ricefish farming mainly focuses on the inlet and outlet， where plastic fishnets， metal nets and mesh woven fish traps are fixed[36]. The mesh size varies depending on the fish size and width. The width of the net is 1.6 times wider than the outlet port， and higher than the ridge. The fish traps are fixed in the shape of a "（" or "∧". At the inlet， the convex surface is outward； at the outlet， the convex surface faces inward. As for the antiescaping facilities for riceturtle farming， due to the characteristics of burrowing and climbing on all four limbs of turtles， the paddy fields should be surrounded with walls built with bricks， cement boards， and wooden boards. The walls should be 50 cm above the ground with the tops stretched inside for 15 cm， and the walls and the stretched tops should be smoothed by painting[40-41].The antiescaping facilities for riceshrimp and ricecrab are similar， and since shrimp and crabs have burrowing and climbing characteristics， the 4 sides of the ridges are built with antiescaping walls using nylon film by burying 10-20 cm at the bottom in the soil and leaving 50-60 cm at the top above the ridge. The film is supported and fixed using wooden stakes or bamboo rafts every 1.5 m. The upper part of the net is sewn with a calcium plastic plate with a width of about 30 cm， presenting an upside down shape[42]. As for the antiescaping facilities for riceloach farming， because of the holedigging habits of the loach， antiescaping boards or antiescaping nets are fixed around the ridges， and the antiescaping boards are buried into the soil over 20 cm deep with about 40 cm above the water surface. 　　Shunlong MENG et al. Research Progress of RiceFish Integrated Farming
　　Safe plant protection techniques RFIF can reduce the incidence of rice diseases， pests and weeds， but it cannot completely replace pesticides. The application of pesticides will affect the survival of fishes in rice fields. How to ensure the safety of fishes while controlling rice pests and diseases in the green paddy field planting mode has become a core technology that restricts the extensive application of RFIF mode. At present， the safe plant protection techniques are mainly ecological control technique， biological control technique and safe pesticide application technique. Ecological control technique is mainly to enhance the natural control capacity of rice to pests and diseases using pest and disease resistant rice varieties[36]， through the cultivation techniques and measures like appropriate early sowing and early planting， rational planting， and scientific regulation of fertilizer and water according to the characteristics of rice growth and the growth characteristics of different fishes. Biological control technique is to give full play to the inhibitory role of fishes to the occurrence of rice pests and diseases in RFIF mode by strengthening the monitoring and early warning of major pests and diseases in rice and adjusting strategies for the control of pesticides， such as planting nectarplanting plants like sesame and soybean along the bank， enticing natural enemies to spawn and breed， using no or less chemical pesticides before the end of July， protecting natural enemies like spiders， and using natural enemies to control rice pests. For example， rice plant hoppers can be controlled through the use of natural enemies. Safe pesticide application technique is to use the pesticides of high efficiency， low toxicity and low residue[43]. Before application， the fish pits and fish ditches should be cleared first， and the water level in the field should be deepened to over 10 cm or slowly released from the field to make the fishes gather in the fish pits and fish ditches[44]. Powder should be sprayed in the morning when there is dew， and aqueous solution should be sprayed after the dew is dry， so that the pesticides can be sprayed on the rice millets[36，38].
　　Safe fertilization techniques Rational fertilization in RFIF system can not only increase soil fertility， promote rice production， but also can facilitate the propagation of food organisms such as planktons and benthos， which can provide abundant food for the fishes. fish species， thereby promoting fish growth. So fertilization is good for rice and fish growth. However， the type， quantity， application time and method of fertilizers have a great influence on the growth of rice and fishes， and high yield and high efficiency can be obtained by proper fertilization. However， overfertilization or improper methods can have a toxic effect on fishes； on the contrary， inadequate fertilization and improper control of time can adversely affect rice growth. Therefore， the correct fertilization techniques can not only solve the contradiction between fertilization and fish farming in paddy fields， but also ensure the coordinated development of planting and breeding， and achieve the purpose of increasing production and increasing efficiency. In general， raising fish in paddy field should follow the principle of "applying enough basal fertilizer， reducing topdressing， taking basal fertilizeroriented fertilization supplemented with topdressing"[43]. At present， the application of organic fertilizers and microbial fertilizers in RFIF mode is an innovation of safe fertilization technique. Organic fertilizers are slowly decomposed after they are applied to paddy fields. They have low toxicity to fishes and crabs， and have longterm fertilizer effects. They can make rice grow steadily and maintain the mediumterm without premature aging. They can also regulate the activity of soil microorganisms， increase the buffering capacity of the soil， and prevent soil compaction and seepage. Microbial fertilizers can promote the absorption of nutrients by rice， produce a variety of physiologically active substances to stimulate the growth of rice， improve the resistance of rice and other effects. Moreover， some organic fertilizers and microbial fertilizers can also be used as fish bait. 　　Fish disease control techniques In RFIF mode， the prevention of fish diseases should be taken as the principle thing. Before fingerling stocking， the fish pits and fish seeds must be fully sterilized， and fish baits and foods also have to be disinfected[45]. Fish ditches and fish pits are generally disinfected with quicklime or bleaching powder； fingerlings are generally soaked with 3-5% saline solution for 10 min[43]. Prevention goes first before diseases occurrence by regularly hanging bags in fish pits. Early treatment is adopted for diseases by using pit drenching method. First， slowly drain away water from the pits to gather fishes in the fish pit nets， then stop draining when the water in the pit is at the same level of that in the paddy field， and then treat the disease according to the symptoms. At the same time， it is also possible to administer medicine baits to cure the diseases， and in the prevalent seasons of fish diseases， the medicine baits can be fed every 15 d.
　　Water quality management techniques In RFIF mode， the surface water level is generally 10-20 cm， the water depth of the fish ditch is 30-40 cm， and the water depth of fish pit is 100-150 cm. In hot summer months， if no fresh water is added to meet the requirements of various water levels， it will inevitably cause the field water to be very hot or even dried， causing the fish to stop eating. If the temperature of the field water is too high， it will affect the growth and development of the fishes and even cause death. Therefore， it is necessary to manage the water and be careful about the water. In places where water is abundant， it is possible to increase the water level， and it is also possible to allow the water to circulate in the field for cooling purposes[46].
　　Research on RFIF techniques by Chinese Academy of Fishery Sciences
　　Domestic research institutes in China have played an important role in the development of RFIF techniques， and some research also reflects to some extent the difficulties and problems faced by RFIF in different periods. The research on RFIF by Chinese Academy of Fishery Sciences has undergone different stages of development. New concepts， new ideas， and new methods have continued to emerge. Since the 1980s， the Chinese Academy of Fishery Sciences has carried out research on fish breeding species， paddy field plant protection techniques， safe application amount of pesticides， and increasing yield and efficiency for RFIF. Since the beginning of the 21st century， the Chinese Academy of Fishery Sciences has carried out indepth studies in areas such as paddy field reconstruction， new variety screening， new technology for plant protection， product quality and safety， and yield and efficiency increase. For example， the mode of rice field culture was improved in the "Integrated Development and Utilization of MiddleLow Yield Fishpond in Dense Waterway net Region" of the Key Science and Technology Project of Jiangsu Province hosted by the Institute of Freshwater Fisheries Research， Chinese Academy of Fishery Sciences in 2001-2004. The RFIF mode was established with fishes （Ctenopharyngodon idellus， Carassius auratus gibelio， Aristichthys nobilis）， crabs， and finless eels as the raising objects， improving the culture benefits. And the research results won the 3rd prize of the Science and Technology Progress Award of the Chinese Academy of Fishery Sciences in 2005. Using temporary raising in ditches with greenhouse supporting technology， research was carried out on the technical specification of pond and paddy field cultivation of Procambarus clarkii" in 2006-2006， which solved the problems of traditional paddy field cultivation of P. clarkii of short growing period， slow growth rate， small size， and low yield. The research results won the 3rd prize of the Science and Technology Progress Award of the Chinese Academy of Fishery Sciences in 2010. In 2010-2015， the study on raising finless eels in paddy field was carried out in the "Technology Research and Experiment Demonstration of Eel Industry" of the Special Fund for AgroScientific Research in the Public Interest. In 2012， the Pearl River Fisheries Research Institute of the Chinese Academy of Fishery Sciences undertook the construction of the Rice Fishery Ecological Fishery Demonstration Park in Liannan Yao Autonomous County of the Project for the Construction Landsaving， Watersaving， Highquality and Highefficiency Fishery Demonstration Zone in Guangdong Province， and carried out research on the breeding of "Procypris merus"， a fish variety of RFIF， and paddy field transformation. The development of the above research work and the popularization and application of research results of the Chinese Academy of Fishery Sciences have played a role in safeguarding the healthy development of RFIF in China. 　　In order to explore the operational mechanism of RFIF ecosystem and establish a standardized production model for RFIF， the Chinese Academy of Fishery Sciences set up the study on the "ricefish integrated ecological farming techniques" of the Key Fundamental Research Funds for the China Academy of Fishery Sciences， and also set up 4 projects to study "fishcrab integrated ecological farming techniques"， "riceshrimp integrated ecological farming techniques"， "ricefish integrated and fishlivestockgrass integrated ecological farming techniques" and "ricecrab integrated ecological farming engineering techniques". Under the joint efforts of the Institute of Freshwater Fisheries Research of Chinese Academy of Fishery Sciences， Yangtze River Fisheries Research Institute， Pearl River Fisheries Research Institute， Fishery Machinery and Instrument Research Institute and Heilongjiang Fisheries Research Institute， basic research was carried out to study the cycle of matters， rational proportion， environmental benefits and economic benefits of RFIF centered on the construction of RFIF mode， matter cycle of the integrated ecological farming system， energy flow and ecologically healthy farming， which laid emphasis on breaking through the key technologies of RFIF system design， main RFIF forms， resource allocation， wastes reclamation， RFIF standardized production system construction， with the aim to set up standardized production technology and mode of RFIF with regional features， establish ricefish production system in which aquatic products and rice can exist together and benefit each other， effectively combine aquaculture with rice farming and facility fisheries， extend the industrial chain， and create a integrated agricultural production method with harmonious environment and excellent overall benefits. At present， the project is proceeding in an orderly manner as planned.
　　Supporting Role of RFIF for Industries
　　At present， as an important way to transfer the mode and adjust the structure of agriculture， RFIF has received extensive and great attention throughout China. The rapid development of RFIF not only expands the development space if aquaculture industry， but also strongly promotes the transformation and upgrading of largescale agriculture， and realizes the quality improving， efficiency enhancing， ecological and environment protected industrial development mode. Therefore， in this sense， RFIF opens up new forms of agricultural production and management， and is an important way for agriculture to achieve coordinated development of economic， ecological and social benefits. 　　Under the vigorous promotion and active guidance of the Ministry of Agriculture and local governments at all levels， RFIF mode and supporting techniques have been continuously improved， and its supporting role to the industry has become increasingly prominent. At present， the yield of rice can be stabilized at more than 7 500 kg/hm2 in the key demonstration area of RFIF established by 13 demonstration provinces （regions， cities） including Jilin Province， Heilongjiang Province， Liaoning Province， Anhui Province， Zhejiang Province， Jiangxi Province， Hubei Province， Fujian Province， Hunan Province， Sichuan Province， Chongqing Municipality， Guizhou Province and Ningxia Province， and the use of chemical fertilizers and pesticides has been reduced by an average of more than half， while the comprehensive benefits of RFIF have increased by more than half[18]. RFIF has opened up a new road for ensuring the supply of aquatic products， achieving the development goal of "promoting rice with fish， improving quality and efficiency， protecting ecoenvironment， and increasing fishing income"， which has played an important supporting role in industrial development.
　　Key Research Directions for RFIF
　　At present， the basic theoretical research on RFIF is weak， and basic theoretical research lags behind industrial development. Due to the weak basic research， the internal mechanism of improving the quality and efficiency of RFIF cannot be fully explained and satisfactorily answered. Moreover， the weak basic theory also limits the healthy， rapid and sustainable development of RFIF. Therefore， it is suggested that the basic theoretical research on RFIF be carried out from the following aspects.
　　Optimization of the farming factors of RFIF system
　　The farming factors in RFIF system can be optimized from the aspects of environmental benefits and economic benefits， and the proportions of suitable fish （shrimp， crab， etc.） and rice in RFIF system can be determined through study.
　　Matter balance characteristics of RFIF system
　　Carbon， nitrogen， and phosphorus are the basic elements of matters， and potassium is an essential element for rice growth. Therefore， with carbon， nitrogen， phosphorus， and potassium as the material elements， RFIF can be divided into aquaculture subsystem and planting subsystem to carry out separate studies on the material balance characteristics of the aquaculture subsystems and the material balance characteristics of the planting subsystems， thus clarifying the material balance characteristics of the RFIF system. 　　Matter circulation law of RFIF system
　　Using carbon， nitrogen， phosphorus， and potassium as material elements， research can be carried out on the transfer and return of matters in RFIF system to clarify the transferring characteristics of matters in RFIF. At the same time， research can be carried out on the inputoutput ratio of carbon， nitrogen， phosphorus， and potassium in RFIF system to clarify the conversion efficiency of matters in RFIF system； and study the carbon， nitrogen， phosphorus， and potassium circulation in RFIF to analyze the rationality of its structure and function， ascertain the matter circulation path and conversion efficiency of the system， and evaluate the ecological effects of the system.
　　Mutualistic symbiosis in RFIF system
　　Research can be carried out on the effect of fish （shrimp， crab， etc.） culture on rice cultivation and the effect of rice cultivation on fish （shrimp， crab， etc.） culture in RFIF to clarify the mutualistic symbiosis of rice and fish in RFIF.
　　Comprehensive benefit evaluation of RFIF system
　　The comprehensive benefit assessment system for RFIF can be constructed from the aspects of economic benefits and environmental benefits to carry out comprehensive benefit assessment of RFIF.
　　Standardized production operation regulation of RFIF
　　There are insufficient systemic studies on rice varieties， stocking time， fish species， individual size， and management methods， and no standardized production practices for RFIF have been established. Therefore， related research still needs further development.
　　Prospects for the Development of RFIF
　　The No. 1 Document of the Central Committee in 2016 pointed out that "it is necessary to promote overall planning for grain， food and feed， integration of agriculture， forestry， animal husbandry and fishery， integration of planting and breeding， and integration of first， secondary and tertiary industries." The No. 1 Document of the Central Committee in 2017 proposed "to promote paddy field integrated farming and lowlying salinealkali land cultivation". Therefore， RFIF meets the policy requirements of the central government to "continue to strengthen the foundation of agriculture， improve agricultural quality and efficiency and competitiveness" and "optimize the industrial structure of products， and focus on promoting agricultural quality and efficiency". RFIF can reduce investment， increase income， and protect the environment， promising with obvious economic and environmental benefits， so it is an agricultural production model with high output， safe products， resourcesaving and environmentfriendly， and the important development direction of agriculture to change the mode and adjust the structure. On October 18， 2016， the China Strategic Alliance for RiceFish Integrated Farming Innovation was set up， marking a new era of comprehensive innovation and development for RFIF. At the inaugural meeting， Director Zhang Xianliang of the Fisheries and Fishery Administration of the Ministry of Agriculture pointed out that "the 13th FiveYear Plan is a period of strategic opportunities for the development of RFIF. It is the moment to develop RFIF". 　　References
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　　Editor： Na LI Proofreader： Xinxiu ZHU