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Arapaima gigas


Arapaima gigas
Araipaima
巨龙
The arapaima, pirarucu, or paiche (Arapaima gigas) is a South American tropical freshwater fish. It is a living fossil and one of the largest freshwater fishes in the world.
Arapaima can reach lengths of more than 2 m, in some exceptional cases even more than 2.5 m and over 100 kg. As one of the most sought after food fish species in South America, it is often captured primarily by handheld nets for export, by spearfishing for local consumption, and, consequently, large arapaima of more than 2 m are seldom found in the wild today.

Commercial fishing of the arapaima has been banned by the Brazilian government due to its commercial extinction. Fishing is allowed only in certain remote areas of the Amazon basin, and must be catch-and-release, or harvesting by native peoples for consumption. Because the arapaima produces "large, boneless fish steaks", it is considered a delicacy; some 7000 tons per year were taken from 1918 to 1924, the height of its commercial fishing. The demand for the arapaima has led to farming of the fish by the "ribeirinhos" (as Brazilians call those living on the riverbanks).

The diet of the arapaima consists of fish, crustaceans, and other small animals. The fish is an air-breather, using its labyrinth organ, which is rich in blood vessels and opens into the fish's mouth, an advantage in oxygen-deprived water that is often found in the Amazon River. This fish is therefore able to survive in oxbow lakes with dissolved oxygen as low as 0.5 ppm. In the wetlands of the Araguaia, one of the most important refuges for this species, it is the top predator in such lakes during the low water season, when the lakes are isolated from the rivers and oxygen levels drop, rendering its prey lethargic and vulnerable.

骨舌鱼科,南美洲鱼类,学名为Arapaima gigas。为世界上最大的淡水鱼之一,长达2.4公尺(8尺)。所属类群具原始特征并有古代化石纪录。尾部因背鳍与臀鳍接近尾鳍而致外形纯圆。鳔具一定呼吸功能。
原产于南美洲亚马逊河。
世界上最大的淡水鱼。最大的个体体长可达2-6米,重可达100千克。体形巨大,长形,稍侧扁。头部骨骼由游离的板状骨组成。口大,无须。无下颌骨,舌上有坚固发达的牙齿。鳔四周富有血管,内表呈蜂窝状,常有特殊的鳃上器。鳞片大且硬,呈嵌镶状。背鳍和臀鳍位于体的后部,互为相对。胸鳍位低。腹鳍位腹部之后。尾鳍圆形。体灰绿色,背部颜色深,腹部较淡,尾鳍及体后部红色。
古老的原始鱼类之一。以鱼、虾、蛙类为食。体型笨重,行动缓慢,是世界上最大的淡水鱼类中的一种。生殖季节挖穴产卵,幼鱼护幼发育达2-3个月,等幼鱼能独立生活后才离开。有的可以长达3米、重达180公斤。由于过度捕捞,现在全世界这样大的淡水鱼已经非常罕见。在南美,巨滑舌鱼是很多保护工程的焦点,包括设置“禁渔保护区”和实施“捕捞配额”等。

骨舌鱼或巨滑舌鱼类是分布在热带的大型淡水鱼,特别是亚马逊河的巨骨舌,可说是世界上最大的淡水鱼。 此类的化石在北美洲和欧洲有发现,因此得知在很早的时候已分布在世界各地的淡水中。鳔有和肺一样的功能,也有和肺鱼相似的愿始型特征。具有美丽且大型的鳞片,常被当作观赏鱼。
骨舌鱼或巨滑舌鱼属于残存的 古生淡水鱼类,据推测最早出现于一亿年前,由于舌中有长出硬骨牙齿,此类的鱼被称为骨舌鱼。类属辐鳍鱼纲真骨鱼部骨舌鱼分部骨舌鱼目骨舌鱼亚目骨舌鱼科,是分布在热带的大型鱼,主要以各种小鱼为食。骨舌鱼身体侧扁像带子,在亚马逊当地叫腰带鱼。亚马逊原产的有双须银骨舌鱼和黑骨舌鱼,东南亚原产的有美丽巩鱼,非洲原产的有异耳鱼,也有澳洲原产的种类。特别是亚马逊河的巨滑舌鱼全长1.5~4.5米,可说是世界上最大的淡水鱼。骨舌鱼为保护卵而将卵存于口中孵化。下颌须能辨别味道,也有确认东西的作用。
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