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Pangasianodon hypophthalmus


Pangasianodon hypophthalmus
Silver Pangasius
银猫
The iridescent shark (Pangasius hypophthalmus) is a species of shark catfish (family Pangasiidae) native to the rivers of Southeast Asia. It is found in the Mekong basin as well as the Chao Phraya River, and is heavily cultivated for food there. It has also been introduced into other river basins as a food source, and its striking appearance and iridescence have made it common in the fishkeeping hobby. Their omnivorous diet consists of crustaceans, other fish, and plant matter
the fish is named for the glow or iridescence exhibited in juveniles, as well as the shark-like appearance of this and other shark catfish. It is also known as Siamese shark or sutchi catfish in the aquarium hobby or as tra, swai (Thai: ปลาสวาย), or striped catfish in the food fish market, and occasionally incorrectly as basa and panga (these names should be rather used for Pangasius bocourti and Pterogymnus laniarius, respectively)
iridescent sharks originate from the large rivers Chao Phraya and Mekong in Asia, though they have been introduced into other rivers for aquaculture. They are a freshwater fish that natively live in a tropical climate. They prefer large bodies of water similar to the deep waters of their native Mekong river basin.
The iridescent shark is a migratory fish that moves upstream to spawn during the flood season while the waters are high and returns downstream to seek rearing habitats when the river water levels recede. Upstream migration in this species appears to be triggered by receding waters. At the end of the flood season, the fish migrate back downstream away from flooded waters. The dates of the migrations vary depending on the river system. In the Mekong river basin, they migrate upstream in May to July and return downstream during September through December. South of the Khone Falls, upstream migration occurs in October to February, with its peak in November to December.
The fins are dark grey or black. Juveniles have a black stripe along the lateral line and a second black stripe below the lateral line; they have a shiny, iridescent color that gives these fish their name. However, large adults are uniformly grey and lack the striping. Adults reach up to 130 cm (4 ft) in length and can weigh up to a maximum of 44.0 kg (97 lb).
However they are not easy fish to keep and are not recommended for home aquariums. Iridescent sharks are schooling fish that prefer to be kept in groups of 5 or more. Accustomed to living in rivers, they are very active fish that require a lot of space. They have very poor eyesight, so any foreign movement they detect outside of their habitat, they will see as an utter threat. If stressed, their first instinct is to flee, and such a blind dash can result in injuries, especially in an aquarium environment. These flights may be terminated by the fish sinking to the bottom, where it may lie on its side or back until it recovers.
Many fish owners are unaware of the enormous size that an iridescent shark can reach and also that they can bite very harshly. If given enough room and fed adequately, an individual of this species can reach 1 m (3 feet) in length. In most home aquariums, the amount of space an iridescent shark has severely stunts its growth. It's for this reason that most iridescent sharks kept in home aquaria grow to only 15 to 30 cm (6 to 12 inches) in length.

淡水鲨鱼属芒科、芒属,是苏氏园腹芒的俗称,淡水鲨鱼又称苏氏圆腹(鱼芒)、虎头鲨、巴丁鱼或八珍鱼,主要分布要东南亚一带,有黑、白、灰三种体色,分河系与海系生长,黑色的称淡水黑鲨,原产于泰国,1978年引进我国;白色的称淡水白鲨,原产于马来西亚,1998年引入我国;灰色的称马来亚河系灰鲨,肉质较好,
1.体型与体色。淡水鲨鱼体色有黑、白、灰、红四种。前三种体色的鲨鱼多作为食用鱼饲养,尤其是灰鲨鱼最受欢迎,其背部青色,体侧青灰色,腹部银白色;红鲨鱼即水晶巴丁鱼,多作观赏鱼饲养。
  2.适应性与食性。淡水鲨鱼耐低氧能力强,适应性广,但抗低温能力较弱。适温20℃~34℃,最佳生长水温26℃~32℃,水温低于18℃时活动缓慢,反映迟钝;水温低于12℃时开始死亡。该鱼食性较杂,幼鱼以浮游动物为饵料,成鱼以水生植物及人工配合饲料为食,饲料蛋白质要求28%~32%。
   3.生长与繁殖。淡水鲨鱼食性杂,食量大,生长速度快,当年鱼苗(3厘米~4厘米)养殖4个月,体重可达0.6千克以上。该鱼性成熟较晚,饲养3年~4年,体重达3千克以上可以进行繁殖。繁殖季节为4月~9月,属一年一次性产卵鱼类。
  该鱼体长、侧扁,背部隆起,头部偏平呈圆锥形,吻短,口亚下位,鳃膜与颊部不相连。膘大,具有呼吸空气的功能,故不易缺氧。该鱼的软骨组织含有硫酸软骨素,故除了作食用和观赏,还具有药用价值。
  4.淡水鲨鱼营底栖生活,属杂食性鱼类,幼鱼以浮游动植物为饵,也摄食人工饲料,成鱼则摄食水生植物和人工饲料。该鱼十分贪食,故生长速度快,个体大,对环境适应性强,河流、池塘均可养殖,养殖8个月可增重1公斤。该鱼性胆怯,游动快捷,受惊扰在水中不停地跳跃。该鱼抗低温能力差,适温20℃-30℃,最佳生长温度是24℃-28℃,当水温降至18℃时,摄食量和活动明显减少,水温连续低于12℃开始死亡;生长水质的ph值为6-7.2。
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