Eriocheir sinensis
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Eriocheir sinensis
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Paddy field used for Chinese river crab culture
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Crab pens in lakes
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Chinese river crab farmer shows his products
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Chinese river crabs ready for transport
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Main producer countries of Eriocheir sinensis (FAO Fishery statistics, 2006)
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DISEASE | AGENT | TYPE | SYNDROME | MEASURES |
Shiver disease | Single-chain RNA virus; rickettsia like organisms | Virus and bacteria | Limbs convulsively shiver or are paralysed; slow movement; decreased response to external stimuli; ceases feeding and becomes inanimate; blackish, greyish or whitish gills; reddish muscle; liver-pancreas become rotten and smelly | Prevention: complete pond disinfection; remove excessive silt; plant aquatic weeds; maintain good water quality and balanced nutrition Treatment: none effective |
Vibriosis | Vibrio anguillarum; V. alginolyticus; V. parahaemolyticus | Bacteria | Rotten abdomen and limbs; body discoloration; whitish lumps formed inside body tissues (especially gills); weakened body and reduced mobility; reduced or no feeding; becomes inanimate | Prevention: use reasonable stocking density, careful handling and maintenance of good water quality; disinfect nursery tank thoroughly with 15–20 ppm KMnO4 solution; dip nursery tools in 50 ppm bleaching powder solution for 1 hr; sterilize freshwater for preparing brackishwater with 10 ppm bleaching powder solution; dose ponds with 1 ppm terramycin Treatment: dose ponds with 2–3 mg/litre terramycin or 1 mg/litre norfloxacin once a day for 3–5 days; use medicated feed with terramycin (0.1–0.2 g/kg of body weight) for 1–2 periods each of 7 days duration |
Sessilinasis | Zoothamnium spp.; Vorticella spp.; Epistylis spp.; Carchesium spp.; Intranstylum spp. | Parasites | Parasites become attached all over body, limb joints and gills; reduced feeding; difficulty in breathing; reduced normal movement; difficulty in moulting and slippery feel to body and limbs | Prevention: use reasonable stocking density; bathe gravid crabs with 10 ppm benzalkonium bromide for 30–50 min. before stocking in hatching tank; dose tanks with 10 mg/litre tea seed cake, replacing half of the water 12 hrs after application Treatment: dose tank with 5–10 mg/litre formalin or 0.7 ppm of a 5:2 mixture of CuSO4 and FeSO4; kill parasites on crab zoea I–II with 50 mg/litre formalin or 30 mg/litre benzalkonium bromide; bathe with 300 ppm benzalkonium bromide for 30–40 min or 500 ppm formalin for 40 min. |
Shell ulcer disease | Vibrio sp.; Pseudomonas sp.; Aeromonas sp.; Spirillum sp.; Flavobacterium sp. | Bacteria | Damaged limb extremities and black ulcer, spreading to every limb segment and central dorsal area; whitish spot on thoracic plate, sunken at its centre and turning to dark-brown ulcer; skin-membrane and muscle visible through rotten holes in shell | Prevention: careful handling; well-balanced nutrition; avoid heavy metal pollution; dose ponds with 15–20 ppm quicklime; maintain good water quality and reasonable depth of bottom silt (5–10 cm) Treatment: dose pond with 2 ppm bleaching powder and use medicated feed (sulfonamides at 0.1–0.2% of feed) for 3–5 days; dose pond with 2.5–3 ppm terramycin once a day for 5–7 days; use medicated feed (0.05–0.1% terramycin) for 1–2 weeks |
Black gill disease | Unidentified bacteria | Bacteria | Gill filaments dark brown at first, turning completely black; slow movement; difficulty in breathing | Prevention: keep suitable depth of bottom silt (5–10 cm); dose ponds with 15–20 mg/litre quicklime once every 15 days during the major epidemic season; regularly add new water to ponds to maintain good water quality Treatment: dose ponds twice with 15–20 mg/litre quicklime |
Sacculina disease | Sacculina sp. | Parasitic barnacle | Parasite found on ventral side or limbs; part of parasite penetrates into body; part remains outside host and forms spore structure attached by stem to crab abdomen | Prevention: treat pond with 10 ppm bleaching powder or 5 ppm dipterex or 100 ppm formalin and remove excessive bottom silt before stocking; avoid using infected crab seed for stocking; stock some common carp to control the parasite Treatment: reduce salinity below 1‰ or transfer crabs to freshwater; bathe crabs with 8 ppm copper sulphate or 20 ppm KMnO4 for 10–20 minutes; dose pond with 0.7 ppm of a 5:2 mixture of CuSO4 and FeSO4 |
China Society of Fisheries. 2004. China Fisheries Statistic Yearbook. 2003 Bureau of Fisheries, Beijing. 122 pp. |
China Society of Fisheries. 2005. China Fisheries Statistic Yearbook. 2004 Bureau of Fisheries, Beijing. 129 pp. |
China Society of Fisheries. 2005. China Statistic Yearbook on Import and Export of Aquatic Products. 2004 China Society of Fisheries, Beijing. 547 pp. |
FAO. 1995. Code of Conduct for Responsible Fisheries. FAO/UN, Rome, Italy. 41 pp. |
Shanghai Green Land Economic Animal Science & Technology Company (ed). 1997. Culture Techniques for Economic Animals - Chinese river crab, mud crab and swimming crab. Shanghai Scientific & Technological Literature Press, Shanghai, China. 109 pp. |
Xianle, Y. 1998. Diagnosis and treatment of major diseases of Chinese river crab. Fisheries Scientific and Technical Information, 25:133-135. |
Xianping, G. 2003. Status and development trend of China's shrimp and crab culture industry. In: Scientific Fish Farming, Add. Issue, Wuxi. 80 pp. |
Xingchuan, X. 2001. Good Culture Practice of Chinese River Crab. China Agricultural Press, Beijing, China. 180 pp. |
Xingchuan, X. & Zhengdong, Z. 1998. Crab culture in Lake. China Agricultural Press, Beijing, China. 208 pp. |
Zhiqiang, W.2000. Culture of Chinese River Crab. China Water Conservancy and Hydropower Press, Beijing, China. 112 pp. |