On The Development Of Chinese Freshwater Fish Culture Technology In The 20th Century

China has a long history in freshwater fish culture. The oracle bone inscriptions excavated from Yin ruins prove that the fish culture of China appeared as far back as at the end of the Shang or Yin Dynasty. In Qing and Han Dynasties Period, Chinese freshwater culture developed from small ponds to large lakes. In Sui and Tang Dynasties Period, the four domestic fishes, i.e., grass carp, black carp, silver carp, and bighead carp, were raised besides common carp. In Song, Yuan, Ming and Qing Dynasties Period, the breeding techniques of four domestic fishes were developed more and more mature, and these laid a foundation for the freshwater fish culture for modern and contemporary China.Zhang Jian, a capitalist in modern times China, while angry with "China has lost its fishery administration for a longtime and many a scholar-bureaucrat even does not know marine power", suggested resolutely to the Business Department that fishery companies should be established. It was served as a prelude to marine fishing industry and freshwater aquaculture industry of modern and contemporary China. But the tangled conflicts and wars among various warlords and the anti-Japanese war before liberation greatly restricted the development of modern China's freshwater aquaculture and its technology. It resulted in Chinese freshwater fishery technology fundamentally having copied the traditional aquaculture technology in the first half of the 20th century, without many changes.After liberation the area of freshwater culture become more and more wide and the output increased gradually. Firstly, the artificial propagation technology of the four domestic fishes gained a great breakthrough, and changed the passive situation of development of fishery on the foundation of collecting natural fry. Secondly, in fish seed culture, the policy of "application of fry began when water was fertilized; and conducted in a scattered and sparse way with combination of manure and diet application" was adopted, in order to continuously upgrade the technical level of fish seed culture in China. For pond aquaculture, the intensive aquaculture methodology was summarized as eight Chinese characters, i. e., water, fingerling, diet, polyculture, high density, rotation, prevention and management. Moreover, aquaculture in lakes, reservoirs and rivers as well as the technology of producing artificial diets and fish disease prevention and treatment achieved considerate successes.The interference and destroy made by Cultural Revolution cancelled the Chinese administrative organizations and some research institutions for fisheries. This caused decrease of the freshwater culture production. But the freshwater fishery in city suburbs still developed considerably, and the culture technology also gained some delectable development, which was mainly reflected in artificial propagation and breeding technology. For example, at that time effective results were gained in artificial propagation research of river eel, barbless carp, Xenocypris davidi Bleeker, Yangtse Sturgeon and China Sturgeon. At the same time, the red mirror common carp growing well was obtained from interspecific hybridization between Xingguo red carp and Russian mirror carp. The Fushou fish deeply welcomed was obtained from interspecific hybridization between Tilapia Mozambican and Tilapia nilotica. The hybrid carp was obtained by hybridization between Xingguo red carp and scattered mirror carp. The Heyuan carp was obtained by hybridization between Hebao red carp and Yuankiang carp. The Furong carp was obtained by hybridization between scattered mirror carp and Xingguo Hebao red carp. The Yue carp was obtained by hybridization between Hebao red carp and xiangjiang common carp. And the normal carp cross bred with crucian was obtained through injecting embryo cell nuclear of black carp, red carp and Hebao red carp into crucian's cytoplasm without nuclear. It conquered the difficulty of distant sexual hybridization. Besides, exploratory tests on fish polyploidy breeding were done, and the diploid red carp and triploid blunt-snout bream with growing ability were obtained. The culture technology was developed. For instance: the fishponds were changed from small to large, from shallow to deep, from collapsed to well and from stagnant water to flowing water; the fish species become more and more; the extensive feeding in large water surface of lake and reservoir developed gradually to intensive or semi-intensive culture; cage culture was operated in lake and reservoir. At that time, on diet research turning up the substitute and tapping diet resources widely were the emphases because that the foodstuff was absent. On the aspect of machinery in this times, oxygen increasing machine was invented. This was a important technology development, and it was effective in controlling the floating head of pondiish and in avoiding the absent oxygen. So it becomes the indispensable fishery machinery for high and stable yield of pond fish culture.After reform and opening, an abroad and profound revolution was happened in fishery economy in China. Aquatic product market was let loose completely. People's enthusiasm at fish farming was triggered. The wavering of China's freshwater culture was broken down and was geared to high speed development. During this period many new techniques were generalized in fingerling culture. For example: amyard-grass was planting widely at lake branch, reservoir bay and pond to feed fingerling; cultivate fish fry with net-cage and pen culture or with straw pulp. Besides, cultivating silver carp fingerling with spiral anabaena; controlling the population size and the community structure of dainty zooplankton at stocking fish fry with dipterex; cultivating fingerlings through industrialized production; increasing the production of normal fish fry greatly through controlling the stocking density, specs and time, increasing oxygen, and exchanging water adopted in adult fish culture. At the aspects of artificial propagation and breeding techniques in that time, the emphasis was put on giant salamander, sweet fish, reeves shad, mullet, long-snout catfish, hemibarbus maculates Bleeker, grey mullet, clarias lazera, yellow fin black porgy, Macrobrachium asperulum, large mouth black bass, fresh water orbfish, freshwater black shrimp, freshwater lobster, turtle, and cirrhina mrigala and so on. Otherwise did hybrid test with Siniperca chuatsi and Siniperca Kneri, with mud carp(♀) and xiang mud carp(♂),with Amur silver crucian carp(♀) and Japanese crucian carp(♂).As a result recomposed double recessive red mirror card, Jian card and Xiang crucian carp with clear characters were gained. And at the same time superior domestic silver carp strains were established. The Nile tilapia and artificial gynogenesis triploid carp with rapid growth were sought out. A batch of supermale fish (YY,♂) were obtained in O.mossambicus. And the text of transferring higher organism's growth hormone to loach was successful. At the aspect of germplasm identification and protection technique, the parameter of evaluating black carp, grass carp, silver carp, bighead carp, blunt-snout bream and mud carp was perfect. And the technologies, which were germplasm identification with biochemistry and molecular biology and studies on the genetic diversity, were applied. Besides, Chinese mitten crab(Eriocheir sinensis) in different water system can be identified; The molecular level average genetic variation degree was determined preliminarily in natural population and artificial propagated population of black carp, grass carp, silver carp, bighead carp, blunt-snout bream and mud carp. About culture technology during this period, compound feeds developed promptly not only in pond but also in lake, reservoir and river. The fish species increased greatly, and the output of different water body was improved significantly through integrated fish culture and ecological fish culture. And at the same time investigation of fishery natural resource and study of administrative division were done widely in medium and large lakes. Artificial stocking, transplantation developed actively. The system engineering of fence culture and the technology of large-scale culture in lake were promoted energetically. The technology of flowing water fish culture with high density such as cold running water, warm running water, river and reservoir flowing water, factory running water, artificial mechanical running water and cyclic running water of assembly biological system was developed. As far as the artificial diet, nutritional component and its requirement dose of aquatic animal were checked out in this period. The fatty acid composition of 20 species of fresh water fish and shrimps was studied systematically. The amino acid, fatty acid and inorganic salt of several freshwater quality products such as whitebait, Chinese soft-shelled turtle were analyzed. The nutrition standard and feed formula of common carp, grass carp and Nile tilapia were made. At the aspect of controlling fish disease in this period not only studied parasitic diseases deeply but also researched other diseases aroused by bacterium, virus, mildew and alga effectively. All of these played an important guarantee role in controlling the freshwater fish disease and in promoting the freshwater fishery. About the culture machinery during this times the mode of dissolved oxygen machine was various, e. g. impeller-type, waterwheel type, jet type, spray type, tube type, pneumonia type, eddy current type, and so on. The aquatic animal fodder pellet mill achieved a further development. In addition, many other types of equipment were developed successfully, for example: automatic feeding machine, dissolved, electric warmer, live fish transport device, and water purifying machine.Based on summary of the development and changes of fresh water culture in 20th in China, we find that the rapid development of fresh water culture technology was the important guarantee for China's freshwater fishery. We also find that the development and changes were affected by state politics, development policy, other natural sciences and education development degree. Although we got great achievement in fresh water culture in 20th,there were some noticeable problems, for example: unbalanced development in different discipline, place and times, weak studies in famous and excellent species propagating, hidden danger in disease and pest control, inadequate research of culture environment, and so on. To achieve the continuous development of fresh water fishery in 21st century in China we must clear away the above obstacles. The urgent affairs is the following aspects: to set up a new development mechanism of fishery sci-tech; to accelerate new scientific and technical revolution of China's freshwater fishery; to improve the ability of science and technology of fishery, especially at the aspects of the following: basic research such as biotechnology, gene technology, control of diseases and insect, feedstuff technology; to import foreign advanced technology of fishery actively; to strengthen government's macro management; to add funds; to popularize science and technology of fishery; to develop fisheries education energetically. Just so the fresh water culture technology and breeding industry can develop continually on higher level in order to make greater contributions for the comprehensive fishery development in China.