Black arowana

Black osteoglossid ( Osteoglossum ferreirai )

The Black osteoglossid ( Osteoglossum ferreirai ) is a large freshwater fish that occurs in northern South America, in the basin of the Río Negro, the Rio Vichada and in the lower reaches of the Río Tomo. The latter rivers are located in eastern Colombia and belong to the basin of the Orinoco. Since the occurring there osteoglossid blacks show no genetic differences to those from the Rio Negro area, it is believed that they were introduced by humans.

Features

The Black osteoglossid is 90 cm long and can not be mistaken as a full-grown animal easily with the Arowana ( Osteoglossum bicirrhosum ). Only metric data distinguish the two species. The Black osteoglossid has 52 to 58 branched fin rays in the dorsal fin, the Arowana only 42 to 50 In the anal fin the ratio 61 to 67 49 to 58 is the anal-fin rays are unbranched. The pectoral fins are supported by a hard and six soft fin rays. The number of scales along the lateral line is 37 to 40 at the Black osteoglossid and 30 to 37 at Arowana, the number of vertebrae is 96 to 100 at the Black osteoglossid and at 84 to 92 at the Arowana. Black osteoglossid have 27 different chromosomes (2n = 54 ), Arowanas 28 (2n = 56 ).

Full-grown black osteoglossid show on its back side, a steel-gray to dark bluish color and are increasingly lighter towards the belly. Dorsal, anal and caudal fins have a yellow or red border. Juveniles are black and show up to a length of 15 cm numerous yellow drawing patterns on the head, trunk and tail.

Way of life

The Black osteoglossid lives near the shore at the surface of rivers and lakes. During the rainy season it migrates into the flooded forest areas. He is an opportunistic predator that smaller fish and other small vertebrates, but above all captured insects and other arthropods. Prey that are on leaves or branches above the water are captured in leaps. Like all osteoglossid is O. ferreirai a mouthbrooders, when the males take the 50 to 250 eggs laid by the female in his mouth and carry it around for about 60 days with them.