Carp (cyprinus carpio) was the earliest fish domesticated by humans, and pond culture began in China as early as the Yin Shang Dynasty. The population and strains of Chinese carp are very rich, including wild species such as Yellow River carp and Heilongjiang wild carp, as well as Jianli carp, Xingguo red carp and Songpu mirror carp. Rich strains of carp culture have also been preserved in the rice field ecosystems in various places, such as Qingtian carp, Jeonju Hehua carp, Phnom Penh carp and so on. Among them, the traditional breeding areas of Quanzhou Hehua carp are mainly in Quanzhou County, Xing'an County and Guanyang County of Guilin City, which is the leading breeding species for the local development of integrated rice and fishery planting and breeding, improving the unit output and comprehensive benefits of rice fields, and is also one of the "business cards" of local characteristic agriculture. "Hehua fish under the wine, the seeer does not go", "the seeer into the table, drink wine and eat fish", "the fish is good to send rice, the pot is also scraped" and other folk proverbs are widely spread, with "rice + grass carp co-cropping" as the main model of the "rice + grass carp co-cropping" as the main model of the "northwest Guizhou mountain rice-fish composite system" is one of the important agricultural cultural heritage of China, its rice and fish farming, hospitality diet, local brands and other Hehua carp-related characteristic industries and social and cultural accumulation are profound, with important agricultural economic value.
rice-fish system
Ecological planting and breeding - rice-fish symbiosis
Rice-fish symbiosis is an ecological planting and breeding mode in which seedlings and fish coexist in paddy fields, which is mainly distributed in southern Zhejiang, northern Fujian, northern Guangdong, southwestern Hunan, northwest Guangxi and southeastern Guizhou. These field fish have adapted to the shallow water environment of rice paddies and are mutually beneficial with rice. On the one hand, the feeding behavior of field fish can reduce the harm of diseases, insects and grasses to riceOn the other hand, the growth of rice also creates a good living environment for field fish. The Rice-Fish Complex System in the Northwest Guizhou Mountains is the sixth batch of China's important agricultural cultural heritage announced by the Ministry of Agriculture and Rural Affairs, covering 59 townships and towns in five counties (cities), including Sanjiang Dong Autonomous County, Rongshui Miao Autonomous County of Liuzhou City, Quanzhou County of Guilin City, Jingxi City and Napo County of Baise City, covering an area of nearly 40,000 hectares. 
Rice fields cultivated by Hehua carp in the mountainous areas of northwest Guangxi.
Germplasm characteristics of C. chinensis
The grass carp got its name from the grass flowers that are eaten in the rice fields. Quanzhou Hehua carp, originated in Quanzhou County, Guilin City, and is also called "Hehua Fish" and "Black Carp" by the locals, which is a characteristic carp breeding strain that has been domesticated and preserved for a long time in the mountainous rice-fish complex system in northwest Guangxi. Compared with other field carp, it has strong reproductive ability, less spines and more meat, delicate flesh, soft bones and no fishy smell, and once enjoyed a high reputation as a court tribute. The characteristic traits of C. hehua carp in Quanzhou are distinct, and the germplasm characteristics are obvious.
Body colorWearing a dark brown "sun-protective suit".
The body surface of the Quanzhou Hehua carp lacks reflective guanine crystals, so the whole body is crystal clear at the fry stage, and the gill cover and abdominal muscles are translucent, which can be described as the "little freshness" of the carp family. In the shallow water environment of the rice field, in order to prevent the sun from causing damage to the body, the pigment cells on the body surface produce more melanin granules, making the body surface dark brown, thus becoming the "black carp" praised by the locals. 
Jeonju grass carp farmed in clear water (melanin increases after sun exposure).
The scales and ** structure of the common carp and the Jeonju grass carp.
Body typeIt has both beautiful curves and a "beer belly".
The Quanzhou Hehua carp cultivated in the rice field are mostly "little fat dun'er" with short body size. The bulge of the abdomen and the gently rising curve between the back of the head give it a soft and plump curvaceous beauty. The rounded "beer belly" is also one of the key factors in the formation of its unique flavor quality. 
Jeonju Hehua carp with a "beer belly".
Normal carp appearanceConsumption characteristicsThe only miniaturized edible carp
The longer photoperiod and higher temperature in the paddy field make the gonads developed and the sexual maturity of the carp earlier. The traditional delicacies of Guangxi characteristics, such as Huang Braised Hehua Fish and Laoyou Hehua Carp, are all selected as ingredients of 30 70 g individuals, and Quanzhou Hehua Carp has become the only miniaturized edible carp in China. Germplasm improvement of C. chinensis
The growth rate of C. chinensis was slow, and the average body weight of 1-year-old fish was 40~13.The 5 g and 2-year-old fish were 665 1250 g, and the growth traits of the group needed to be improved if rice and carp were to be harvested and marketed at the same time. In 2017, with the help of Guilin Lvmiao Ecological Agriculture, Guangxi Academy of Fishery Sciences collected 321 males and 251 females from the paddy fields of 13 farmers in Quanzhou County, and used the method of family breeding to improve the growth rate of G0-G2 generations, and analyzed the phenotypic parameters of their body weight and body length traits according to the improved data from 2017 to 2020, and estimated the breeding progress of related genetic parameters.
Phenotypic parameters of body weight and body length traits
The lowest coefficient of variation of the mass of the 160-day-old C. grass carp in Quanzhou was 050. Up to 072, and the lowest coefficient of variation of body length was 019. The highest is 022, which are at the highest level compared with the current farmed species. The uniformity of the population is extremely low, and the production needs to be sieved in stages to obtain individuals with consistent specifications**, and the labor cost is high. Therefore, improving population uniformity is one of the important goals of germplasm improvement in Quanzhou. 
Data distribution of body weight and body length traits of C. grassGenetic assessment of selective traits
The heritability of body weight traits was low (h2<0.) as assessed by mixed linear model15), the phenotypic correlation between body weight and body length traits was 099, and the genetic correlation is 092, the obtained genetic parameters are within reasonable intervals. However, the number of breeding families and control families constructed in each generation is small, and the selection generation is also small, which may cause a large errorIn addition, due to the influence of the year and the breeding environment, the environmental variance may be smaller than the true value.
Power correlation plot of body mass and body length of grass carp.
Breeding progress
By measuring the body weight and body length indexes of 3 699 individuals from 121 families of G0, G1 and G2 generations of C. chinensis, and using a mixed linear model to evaluate the breeding progress, the results showed that the genetic progress of body weight traits estimated by the least squares value of the target trait and the breeding value of the target trait was 1282% and 1545%, and the genetic progression of body length trait was 276% and 660%, and the growth rate of the breeding group was significantly improved. Combined with the characteristics of high genetic diversity and sexual maturity at the first instar, it is expected that considerable improvement effects can be obtained in the short term by selecting the technical route with easy operation and high selection intensity. Related Articles:
Du Xuesong, Chen Zhong, Wen Luting, Pan Xianhui, Huang Cheng, Zhou Kangqi, Lin Yong, Li Zhe, Luo Hui, Qin Junqi*Estimation of genetic parameters of body weight and body length of C. chinensis and its breeding progress[J].South China Fisheries Science, 2022, 18(6): 69-77
Written by |Du Xuesong.
Edit |Jiang Rui.
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