The African arowana, Heterotis niloticus, is a member of the arowana family. Despite being called an "Arowana", the African arowana is more closely related to Arapaima gigas, the only other member in the subfamily Heterotidinae. The only plankton-feeding osteoglossid, the African arowana has a more terminal mouth than other species of arowana (Osteoglossum

Osteoglossum

Osteoglossum is a genus of fish in the family Osteoglossidae. The genus contains two species: the silver arowana and the black arowana . They reach almost in length and are restricted to freshwater habitats in tropical South America....

and Scleropages

Scleropages

Sceleropages is a genus of freshwater fishes found in Asia and Australia. Six species are currently recognized. All are carnivorous and have great jumping ability. Most are endangered in the wild to some degree. Scleropages species are highly valued as aquarium fish, particularly by those from...

).

Description

Like the other Osteoglossids, the African arowana is a long-bodied fish with large scales, long dorsal and anal fins

Fish anatomy

Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...

 set far back on the body, and a rounded caudal fin. Its height is 3.5 to 5 times Standard Length

Fish measurement

Fish measurement refers to the measuring of the length of individual fish and of various parts of their anatomy. These data are used in many areas of ichthyology, including taxonomy and fisheries biology.-Overall length:...

 (SL). It has been reported to reach up to 100 cm (39 in) SL and weigh up to 10.2 kg (22 lb).

This fish is gray, brown, or bronze in color. Coloration is uniform in adults, but juveniles often have dark longitudinal bands.

African arowanas have air-breathing organs on its branchiae, enabling them to survive in oxygen-depleted water. A suprabranchial organ allows it to concentrate small planktonic food particles and also has a sensory function.

Range

This species is widespread throughout Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, where it is native to all the watersheds in Sahelo-Sudanese region, Senegal

Senegal

Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...

, and Gambia as well as parts of eastern Africa. This range includes the basins of the Corubal

Corubal River

The Corubal is a river of West Africa, a major tributary of the Geba River. It rises near Labe on the Fouta Djallon plateau of Guinea, enters Guinea-Bissau on its eastern border, then meanders generally southwest, nearing the Guinea-Bissauan border, then turns northwest, passes by Xitole, then...

, Volta

Volta River

The Volta is a river in western Africa that drains into the Gulf of Guinea. It has three main tributaries—the Black Volta, White Volta and Red Volta...

, Ouémé

Ouémé River

The Ouémé River is a river in the countries of Benin and Nigeria. It flows into the Atlantic Ocean near the large city of Cotonou, Benin .Also known as the Weme River, this river has its source in the Atakora Mountains of Benin...

, Niger

Niger River

The Niger River is the principal river of western Africa, extending about . Its drainage basin is in area. Its source is in the Guinea Highlands in southeastern Guinea...

, Bénoué, and Nile Rivers as well as those of Lake Chad

Lake Chad

Lake Chad is a historically large, shallow, endorheic lake in Africa, whose size has varied over the centuries. According to the Global Resource Information Database of the United Nations Environment Programme, it shrank as much as 95% from about 1963 to 1998; yet it also states that "the 2007 ...

 and Lake Turkana

Lake Turkana

Lake Turkana , formerly known as Lake Rudolf, is a lake in the Great Rift Valley in Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake...

. It has been successfully introduced to Côte d'Ivoire

Côte d'Ivoire

The Republic of Côte d'Ivoire or Ivory Coast is a country in West Africa. It has an area of , and borders the countries Liberia, Guinea, Mali, Burkina Faso and Ghana; its southern boundary is along the Gulf of Guinea. The country's population was 15,366,672 in 1998 and was estimated to be...

, the Cross River

Cross River (Nigeria)

Cross River is the main river in southeastern Nigeria and gives its name to Cross River State.It originates in Cameroon, where it takes the name of the Manyu River....

 in Nigeria

Nigeria

Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...

, the Sanaga

Sanaga River

The Sanaga River is a river of South Province, Cameroon, Centre Province, Cameroon, and West Province, Cameroon. Its length is 890 kilometers.The Sanaga River forms a boundary between two tropical moist forest ecoregions...

 and Nyong

Nyong River

The Nyong is a river in Cameroon. The river flows approximately 640 km to empty into the Gulf of Guinea.-Transport:The town of Mbalmayo, which has a railhead, lies on the north bank of this river. The towns of Akonolinga and Abong-Mbang also lie on it....

 rivers in Cameroon

Cameroon

Cameroon, officially the Republic of Cameroon , is a country in west Central Africa. It is bordered by Nigeria to the west; Chad to the northeast; the Central African Republic to the east; and Equatorial Guinea, Gabon, and the Republic of the Congo to the south. Cameroon's coastline lies on the...

, and Ogooué River

Ogooué River

The Ogooué , some 1,200 km long, is the principal river of Gabon in west central Africa. Its watershed drains nearly the entire country of Gabon, with some tributaries reaching into the Republic of the Congo, Cameroon, and Equatorial Guinea....

 in Gabon

Gabon

Gabon , officially the Gabonese Republic is a state in west central Africa sharing borders with Equatorial Guinea to the northwest, Cameroon to the north, and with the Republic of the Congo curving around the east and south. The Gulf of Guinea, an arm of the Atlantic Ocean is to the west...

, as well as the lower and middle Congo River

Congo River

The Congo River is a river in Africa, and is the deepest river in the world, with measured depths in excess of . It is the second largest river in the world by volume of water discharged, though it has only one-fifth the volume of the world's largest river, the Amazon...

 basin, including Ubangui and Kasaï

Kasai River

The Kasai River is a tributary of the Congo River, located in central Africa. The river begins in Angola and serves as the border between Angola and the Democratic Republic of the Congo , then flows into the DRC, where it joins the Congo northeast of Kinshasa. The Kasai's tributaries include the...

 Rivers. It has also been introduced in Madagascar

Madagascar

The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

. In some cases, introduction is reported to have had a negative impact on the local ecology.