Food and Agriculture Organization of the United Nationsfor a world without hunger
Fisheries and Aquaculture Department
Body laterally compressed and thick, round abdomen; standard length 2.1-2.8 times body height and 3.1-4.1 times head length; length of head larger than body height; small and short head; short snout; terminal mouth and arch shaped; lower jaw slanting upwards slightly; thick lip; no palpus; 37-54 gill rakes on the first outer gill arch, gill rake long; one row of pharyngeal teeth on each side, laterally compressed, formula 4--4; 27-30 scales in lateral line. Tip of pectoral fin can reach the base of ventral fin; dorsal fin ray: 3, 15-19; pectoral fin ray: 1, 16-17; ventral fin ray: 1, 8; anal fin ray: 3, 5; body colour: silvery grey, deeper colour in dorsal portion, lighter colour in abdomen; colour of fins: greyish.
The culture of crucian carp was initiated in China. The earliest activity can be traced back to the East Han Dynasty (25-189 A.D.), according to archaeological studies, to the Song Dynasty (960-1279 A.D.) and according to written records. However, production was limited to a rather small scale. Aquaculture of this species was limited to China and Japan until the mid-1960s. Since then it has gradually expanded to many other countries and regions, including Taiwan Province of China, Belarus, Republic of Korea, and Uzbekistan. The major producer has always been China, whose production has expanded from less than 2000 tonnes in 1950 to nearly 1.7 million tonnes in 2002 (99.6 percent of the global total).
Crucian carp is a freshwater fish that inhabits lakes, rivers and reservoirs in various countries in Asia and Europe.
They normally dwell in the bottom layer of the water column. Comparatively, they can tolerate a wide range of environmental conditions. They are sedentary fish, which can propagate naturally in various types of water bodies, such as rivers and lakes. Crucian carp is basically an omnivore that naturally feeds on organic detritus, filamentous algae, small benthic animals, and pieces and seeds of aquatic weeds. However, the fry/larvae feed on zooplankton. In addition, in aquaculture, they well accept artificial feed, such as by-products from grain processing and oil extraction, and pelleted feed. Rainfall, water level and temperature changes are the stimuli for reproduction. The presence of aquatic weeds is also important for spawning; they serve as the substrata for the eggs, which are adhesive. Crucian carp is a medium-size fish with a moderate growth rate that can reach 1.25 kg.
The major system used for rearing crucian carp is earthen pond culture, but rice paddies are also used in some areas of China.
Earthen ponds are used for both spawning and nursing of crucian carp. The pond size is usually 0.07-0.2 ha and 1.5-2.0 m deep. Ponds are chemically cleared to eliminate all harmful organisms after totally drying; quicklime is the most commonly used chemical for eradication, usually applied at 900-1125 kg/ha. Organic fertilizer (animal and green manure) is commonly applied 5-10 days before stocking, depending on the water temperature, to increase the biomass of natural food organisms (zooplankton). The quantity of organic fertilizer used is usually 3000 kg/ha for animal manure or 4500 kg/ha for green manure. Green manure and animal manure may be used simultaneously, but the quantity of each is reduced accordingly.
Artificial propagation forms the major supply of seed for the culture of crucian carp nowadays, although natural seed is available in various types of water bodies. At present, the most commonly cultured crucian carp is Carassius carassius gibelio, which is produced through gynogenesis with female Carassius carassius gibelio and male Xingguo red common carp. Such heterogenous gynogenesis provides all-female offspring, whose growth rate is 30-40 percent higher than the original fish. Other species and strains of crucian carp are also cultured in various areas of China.
Well-selected mature broodstock are released into spawning tanks/ponds/cages. Hormone injection is optional, since the fish can spawn well without it. However, hormone injection enables the fish to spawn more synchronously. The most important technique is to provide substrata of grass bundles, palm leaves, fine tree branches and plastic weeds in the water column of spawning facilities in which egg attachment can take place. Eggs can be hatched in earthen ponds where harmful organisms have been eliminated in advance. The eggs are simply moved into the spawning pond together with the substrata and fixed in the water column.
For better hatching, eggs can also be hatched in running water (raceway or jar). The substrata with eggs attached can simply be hung in the water column. The eggs can also be removed from the substrata for hatching in raceways or jars. Egg adhesivity is removed by mixing with clay solution prior to stocking. The hatchlings (fry) are transferred to nursery ponds when they are able to swim well and feed actively.
Monoculture is the normal method for the nursery stage. The stocking density is usually 1.5-2.25 million/ha; the exact level depends on the length of the rearing period (2-3 weeks, which in turn mainly depends on water temperature) and the size required. Organic fertilization is carried out, ranging from 1 500-3 000 kg/ha every 4-5 days for animal manure or green manure, depending on water fertility. Soybean milk may also be used as both direct feed and fertilizer, to replace organic fertilizers in the nursery operation; the usual application level is 3-5 kg (dry soybean)/100 000 fish daily. The use of soybean normally increases production costs, but it is an easy method to handle. The application of a paste-form of soybean cake or other by-products from grain processing is required from the 5th day after stocking, usually applied at 1.5-2.5 kg/100 000 fish daily. Normal survival rates in nursery ponds are 70-80 percent, although they may reach over 90 percent under good management.
The fish usually reach the size of about 30 mm after 2-3 weeks. These are called summer-fingerlings in China and are then ready for fingerling rearing. Conditioning through careful netting and holding the fish at high density for a while (several hours) is required before transferring the summer-fingerlings to fingerling ponds; this practice increases the tolerance of the fish to transport stress.
Summer-fingerlings are not suitable for direct stocking in grow-out ponds. They need to be reared to a larger size (6-7 cm or larger) first. Fingerling rearing can be carried out in two different ways:
The most commonly adopted ongrowing techniques are polyculture in ponds/pens and rice paddies. Crucian carp is a bottom fish with relatively slow growth and production may often be relatively limited.
Polyculture in ponds/pens (semi-intensive to intensive)
In this system, crucian carp may be stocked either as the major species or as a secondary species, together with other carps. When crucian carp are the major species, the stocking rate is 22 500-30 000/ha of 25-50 g fish. Silver and bighead carp are also stocked as secondary species. After one year, the fish usually reach 150-400 g and production can reach 4000-6000 kg/ha. The production of secondary fish can also reach 3000-4500 kg/ha, giving a total productivity of 6000-10 000 kg/ha.
When crucian carp is the major species, the fish are mainly fed with commercial feeds. Crucian carp are omnivores that feed on both natural food and commercial feeds. Pelleted feed is becoming more popular when crucian carp is the major species in grow-out. Feed ingredients of pelleted feeds mainly consist of by-products from oil extraction (such as soybean cake) as the major protein source, and grain processing. The addition of animal protein (fish meal) is very limited (<10 percent), so the feed is relatively cheap. FCR as ~2:1. Fertilization can reduce the quantity of feed needed by enhancing natural food availability.
Crucian carp can also be stocked as a secondary species; in this case the stocking density is normally 1500-1800 fish/ha of 7-10 cm fish. Finally, the fish can reach 300 g and crucian carp production can achieve 450-900 kg/ha, which usually accounts for 5-10 percent of total production. When cultured as a secondary species, no special feeding is required for the fish. Crucian carp can also be cultured as secondary species in pens in shallow lakes; stocking and production levels are similar to pond culture.
Extensive culture in rice paddies
Crucian carp is also suitable for culture in rice paddies; stocking rates are 750-1500/ha. The fish mainly feed on natural food. Production can reach 300-450 kg/ha. This form of culture is also beneficial to rice, as a means of pest control and tilling the soil.
Crucian carp, being a bottom-dwelling fish, are difficult to harvest effectively without draining the pond. Harvesting takes place at the end of the culture period firstly by netting at a reduced water depth, followed by total harvesting after drainage. Selective harvesting is also practiced by some farmers for balanced marketing; in this case the normal method is to use a casting net.
Farmed crucian carp is entirely sold live or fresh. Drying and salting is only used for crucian carp caught from natural water bodies (rivers and lakes) by some traditional inland fishers.
This varies according to the culture practice used but is normally below USD 0.70/kg.
The major disease problems affecting crucian carp are included in the table below.
In some cases antibiotics and other pharmaceuticals have been used in treatment but their inclusion in this table does not imply an FAO recommendation.
Suppliers of Pathology Expertise
Assistance can be obtained from the following sources:
The total value of cultured crucian carp production globally was USD 1.20 billion in 2002, representing an APR of 15.4/yr. This apparently slower rate of expansion in value is mainly due to the devaluation of Chinese currency against the US dollar.
At present, crucian carp is basically a locally consumed product. Traditionally, crucian carp is consumed fresh. Almost all cultured production is marketed live or fresh; there is almost no processing, except a small quantity of dry/salted fish produced from wild-caught fish. Crucian carp has a moderate price that is affordable to middle- and low-income people. There has been a considerable decline in the global average unit value of crucian carp in the last 10 years according to FAO data; by 2002 it was only USD 0.704/kg. There is a big gap between this figure and the retail market price, which has ranged between USD 0.90-1.30/kg in recent years. There is no specific control over the marketing of crucian carp as it is basically for local consumption.
Crucian carp has been cultured for nearly 2000 years in China. However, it was not considered as an important species due to there being an abundant resource in natural water bodies and its relatively slow growth. Efforts to develop of culture techniques and other related studies were very limited before the mid-1980s; since then, more efforts have been made in research and development as it has taken a more important position in Chinese aquaculture. Improving growth performance has been a priority. Application of heterogenous gynogenesis in crucian carp achieved substantial progress in this respect. Many improved strains have been developed through this technique with various varieties of Carassius carassius gibelio (female) and common carp (male); these usually give 30-40 percent higher growth rate than the parent fish and 2-3 times more than other crucian carp varieties. More recently, tetraploids of heterogenous gynogenesis crucian carp were successfully developed, which not only improves growth performance but also rules out the possibility of contaminating the natural population with genetically modified fish.
As noted above, output in Taiwan Province of China and Japan has declined in recent years. This may be because of changes in consumer demand. Despite its delicious taste and fine meat texture, crucian carp contain a large quantity of fine inter-muscular bones, which may limit acceptance by the modern consumer. Producing larger fish (about 500 g) could significantly alleviate this problem.
Other research work has been focused on the control of the significant diseases of crucian carp. The best-studied disease is bacterial septicemia. Preventative and curative methods have been thoroughly studied. Nutritional studies and the development of compound feeds for crucian carp are far behind but pelleted feeds are more and more commonly used in intensive culture.
Crucian carp is a preferred fish in most parts of China, due to its good meat quality and high nutritional value. Progress in genetic improvement has significantly improved growth rates, and enhanced the marketable size. This makes crucian carp more competitive and better accepted by consumers. Therefore, the prospect for further increases in production in China is quite positive; rapid expansion in production in recent years is good evidence of this. However, it may be a different picture in other countries. The most significant disadvantage of this species is the large number of fine inter-muscular bones, which makes it difficult to eat for people that are not accustomed to this. It is thus very unlikely that there will be a rapid increase in production outside China in the near future, or for crucian carp to become an important item in the international market.
Crucian carp is an omnivore, and a very suitable secondary species in polyculture in ponds and pens. It is also a good for rice-paddy culture. In these cases it does not need special feeding and there is no negative impact on the environment or other fish. However, its intensive culture as a major species is more dependent on pelleted feed. Accumulation and discharge of various wastes to natural water bodies may cause adverse impacts. In addition, genetically improved strains may have an impact on the natural germplasm as the fish can breed naturally in various kinds of inland water bodies.
At least three issues need to be addressed in considering responsible aquaculture practices for crucian carp culture:
China Society of Fisheries. 2003. 2002 China Statistic Yearbook on Import and Export of Aquatic Products. Beijing. China. China Society of Fisheries, Beijing, China. 356 pp.
De Silva, S. 2003. Carps. In: J.S. Lucas ∧ P.C. Southgate (eds.), Aquaculture: farming aquatic animals and plants, pp. 276–294. Blackwell Publishing, Oxford, England.
EIFAC. 2001. Report of the Ad Hoc EIFAC/EC Working Party on Market Perspectives for European Freshwater Aquaculture, Brussels, Belgium, 14–16 May 2001EIFAC Occasional Paper No. 35. FAO, Rome, Italy. 136 pp.
Guocheng, Y. 1998. Techniques and Experiences for High Production and Efficiency Freshwater Aquaculture. China Press of Science & Technology, Beijing, China. 415 pp.
Jinpei, P.1988. Handbook for Diagnosis and Treatment of Fish Diseases. Shanghai Press of Science and Technology, Shanghai, China. 166 pp.
Pillay, T.V.R. 1990. Aquaculture: principles and practices. Fishing News Books (Blackwell Scientific Publications), Oxford, England. 575 pp.
Renkui, C.1991. Development History of Freshwater Culture in China. China Press of Science & Technology, Beijing, China. 309 pp.
RLCC. 1989. Integrated Fish Farming in China. NACA Technical Manual No 7. NACA, Bangkok, Thailand. 278 pp.
Wu, W.. 2000. Fish Culture and Enhancement. China Agricultural Press, Beijing, China. 661 pp.
Xianwen, W. 1964a. Ichthyography of Cyprinidae in China (Upper Volume). Shanghai Science and Technology Press, Shanghai, China. 230 pp.
Xianwen, W. 1964b. Ichthyography of Cyprinidae in China (Lower Volume). Shanghai Science and Technology Press, Shanghai, China. 598 pp.