A large freshwater fish belonging to the family Osteoglossidae in the order Osteoglossiformes of the class Osteoglossini. It is found in the Amazon River basin and some rivers in the Guiana region, where it lives in areas with gentle currents. Its name comes from its place of origin. It can reach a total length of 1 meter, and its body is elongated and laterally compressed. Its mouth is large and points diagonally upwards, and it has two barbels at the tip of its lower jaw. Its dorsal and anal fins are low and long. Its scales are large. Its body color is silver, with a beautiful iridescent sheen. It is a bony fish with primitive morphological characteristics, and is also famous as a mouth breeder, which incubates eggs in its mouth. The hatched larvae have a large orange umbilical sac. It is carnivorous. It is kept as an ornamental fish, and the optimum water temperature is 25-30°C, and water quality should be slightly acidic to neutral. A close relative is the black arowana (Osteoglossum ferreirai) from the Rio Negro. Other genera in the same family include the Scleropages from Southeast Asia and Australia, and the Heterotis from Africa, all of which are known as arowana in the tropical fish market. [Taki Yasuhiko] [Reference] |Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend |
硬骨魚綱オステオグロッスム目オステオグロッスム科に属する大形淡水魚。アマゾン川流域とギアナ地方の川の一部に分布し、流れの緩やかな所にすむ。名は原産地の呼び名である。全長1メートルに達し、体は細長く、側扁(そくへん)する。口は大きく、斜め上を向き、下あごの先端に2本のひげがある。背びれと臀(しり)びれは低くて長い。鱗(うろこ)は大きい。体色は銀色、美しい虹色の輝きがある。原始的な形態的特徴をもつ硬骨魚で、卵を口の中で孵化(ふか)するマウスブリーダー(口中哺育魚(ほいくぎょ))としても有名である。孵化した仔魚(しぎょ)はオレンジ色の大きな臍嚢(さいのう)をもつ。肉食性。観賞用に飼育され、適水温は25~30℃、水質は弱酸性から中性がよい。近似種にリオ・ネグロ産のブラックアロワナOsteoglossum ferreiraiがある。同科の他属に東南アジアやオーストラリア産のスクレロパゲスScleropages、アフリカ産のヘテロティスHeterotisがあり、熱帯魚市場ではいずれもアロワナの名でよばれている。 [多紀保彦] [参照項目] |出典 小学館 日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について 情報 | 凡例 |
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