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Gymnarchus niloticus


Gymnarchus niloticus
Aba Aba
反天刀
Gymnarchus niloticus – commonly known as the aba, aba aba, frankfish, freshwater rat-tail or African knifefish – is an electric fish, and the only species in the genus Gymnarchus and the family Gymnarchidae within the order Osteoglossiformes. It is found exclusively in swamps and near vegetated edges in the Nile, Turkana, Chad, Niger, Volta, Senegal, and Gambia basins.

G. niloticus has a long and slender body, with no caudal, pelvic, or anal fins. The dorsal fin is elongated, running along the back of the fish towards the blunt, finless, tail, and is the main source of propulsion. It grows up to 1.6 metres in length and 19 kilograms (42 lb) in weight.
G. niloticus is nocturnal and has a poor vision. Instead, it navigates and hunts smaller fish using a weak electric field similar to that of the related elephantfish. Also like the elephantfishes, it possesses an unusually large brain, which is believed to help it interpret the electrical signals. It can make its tail negatively charged with respect to its head. This produces a symmetrical electric field around its body. Nearby objects distort this field, and it can sense the distortion on its skin.
G. niloticus lay their eggs in floating nests up to a metre across. The adults continue to guard the young after hatching.

 一种古老的大型淡水鱼类,为单一种、属,属长颌鱼目,没有腹鳍、尾鳍,反应灵敏,可作出快速后退游动,个性凶暴,下颚强而有力,视力较弱,靠尾部发电组织发出微弱电流辩识周围环境与退敌;日间常躲在角落,在夜间会主动攻击同缸中大小体形鱼只,且寿命较长,最好单独饲养。
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