Arapaima
Arapaima in the Aquarium of the Cologne Zoo.
Arapaima (synonyms: Sudis Cuvier, 1816; Vastres Valenciennes, 1847), known in South America Pirarucu or paiche, a freshwater fish species from the order of Knochenzünglerartigen is ( Osteoglossiformes ). Arapaima means "red fish " in the Tupi- Guarani languages. Arapaimas are among the largest freshwater fish in the world. They can be about two feet long and can reach a weight of over 100 kg.
Dissemination
Arapaimas come between 5 ° north and 11 ° south latitude in northern South America in the Amazon and the lower reaches of its southern tributaries of the Rio Madeira, Rio Tapajós and Rio Xingu, in the larger watercourses Marajó Island at the mouth of the Amazon, in the tributaries of the Amazon headwaters Pastaza, Rio Pacaya and Río Ucayali, in the Araguaia River and the lower reaches of the Rio Tocantins and in the south of the island Capim Marajó. In coming from the south rivers he lives only in the past in the lowland sections, not above the rapids that make up these rivers as they flow from the Sierra into the actual Amazon basin. In the northern Amazon tributary Rio Negro missing the fish, because they can not find enough food in its nutrient-poor blackwater. However, they occur in the tributaries of Rio Branco, Rio Jufari and in the lower reaches of the river Demin. The Rio Branco leading white water. In Guyana Arapaimas live in Essequibo. The preferred temperature of the Arapaimas is 25 ° C to 29 ° C, the preferred pH of 6.0 to 6.5.
Features
Arapaima can be over 2 meters long. The largest known specimen was 2.32 m long and had a weight of 133 kg. It is usually, but with a length of up to two meters. An often quoted statement by Robert Hermann Schomburgk from 1836 of 4.5 m (15 feet) long and about 186 kg ( 410 pounds) heavy specimens is implausible, since such a large Arapaimas would be much harder. Because of this unreliable, based only on hearsay Arapaima gigas size specification was often referred to as the largest freshwater fish in the world. But length default, it is on the order of the European catfish and well below Himantura polylepis, one occurring in the basins of the Mekong and Chao Phraya stingrays. Schomburgk handed a presumptuous of him copy a length of 2.46 m (8 feet and 1 inch ).
The body is elongated and the Arapaimas round in cross section. It is olive green and shows a lot of silvery sheen. At large scales, there are crescent-shaped rust-colored or orange-red spots. The iris is yellow or red. In the lateral line series (SL ) are 35 or 36 scales in a line perpendicular to the longitudinal axis 3 to 3.5 scales on each side of the body. The dorsal fin is supported by 20 to 24, the longer anal fin from 26 to 40 fin rays.
The fish take in atmospheric air. To this end, they rise to the surface and take the air with a loud, distinctive sip to himself. They have a constant upper jaw.
Reproduction
Arapaimas spawn in April and May. To achieve this, the fish on sandy soils a nest of half a meter in diameter and a height of 15 cm. Eggs and juveniles are guarded.
System
The genus was described in 1843 Arapaima by the German physician and naturalist Johannes Peter Müller. Type species of the genus is Sudis gigas Schinz 1822 ( Arapaima gigas = ). Three other species were described in 1847 by French zoologist Achille Valenciennes, 1868 synonymized by Müller in a short writing without detailed analysis with Arapaima gigas Arapaima which was monotypic. This was true for the following 145 years, until the American ichthyologist Donald J. Stewart in 2013 first descriptions and type specimens (if any ) new analyzed and the types revalidated, as well as Arapaima leptosoma a new species described.
Arapaima belongs to the family of Arapaimidae to the otherwise only the African osteoglossid ( Heterotis niloticus ) is one. The American ichthyologist Joseph S. Nelson orders the family under the name Heterotidinae as the subfamily Knochenzünglern ( Osteoglossidae ) to.
Species
- Arapaima agassizii ( Valenciennes, 1847)
- Arapaima gigas ( Schinz, 1822)
- Arapaima leptosoma Stewart, 2013
- Arapaima mapae ( Valenciennes, 1847)
Endangering
Arapaimas are endangered by overfishing. However, the IUCN can not specify levels of hazards, as no adequate data.