The reticulated knifefish (''Papyrocranus afer'') is a species of freshwater fish in the family

Notopteridae The family Notopteridae contains 10 species of osteoglossiform (bony-tongued) fishes, commonly known as featherbacks and knifefishes. These fishes live in freshwater or brackish environments in Africa and South and Southeast Asia. With the denot ...

, the featherbacks, found in tropical

West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Maurit ...

. It reaches a maximum length of and a reported weight of .

Description

The reticulated knifefish usually grows to a length of about . It is laterally flattened and has very small scales. Like other featherbacks, the dorsal fin projects from its back rather like a feather; this fin has no spines and just two soft rays. The fish has an elongated anal fin with no spines and between 113 and 141 soft rays. This is united with the small caudal fin. There are no pelvic fins. The anal fin provides propulsion, either forwards or backwards, undulating from side to side with a rippling movement.

Distribution

This fish is native to tropical West Africa. It occurs in the

Niger ) , official_languages = , languages_type = National languagesTano River The Tano or Tanoé River is a river in Ghana. It flows for 400 kilometres from a town called Traa a suburb of Techiman the capital town of Bono East Region of the Republic of Ghana to Ehy Lagoon, Tendo Lagoon and finally Aby Lagoon in Ivory Coast ...

and

Pra River Pra River may refer to: *Pra River (Ghana) The Pra River is a river in Ghana, the easternmost and the largest of the three principal rivers that drain the area south of the Volta divide. Rising in the Kwahu Plateau near Mpraeso and flowing sout ...

basins in Ghana, and the Cross River and

Sanaga River The Sanaga River (formerly german: Zannaga) is the largest river in Cameroon located in East Region, Centre Region and Littoral Region. Its length is about from the confluence of Djérem and Lom River. The total length of Sanaga-Djérem Rive ...

basins to the east of the

Niger Delta The Niger Delta is the delta of the Niger River sitting directly on the Gulf of Guinea on the Atlantic Ocean in Nigeria. It is located within nine coastal southern Nigerian states, which include: all six states from the South South geopolitical ...

Ecology

Besides breathing in the normal way through its gills, the reticulated knifefish is able to breathe air at the surface of the water. For this purpose the

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled Organ (anatomy), organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their curren ...

acts as a lung; it is an elongated structure that extends for the length of the body cavity and has finger-like side projections. This adaptation allows the fish to live in swamps where the water would otherwise be too low in

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

content. The swim bladder can also be used to create sounds. The reticulated knifefish produces a small number of relatively large eggs; the average fecundity is 500 eggs/kg of bodyweight, the eggs having a diameter of . The large eggs results in large larvae which may have a better chance of survival in inhospitable surroundings. The reticulated knifefish is among a small group of

teleost Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tel ...

fish to be

electroreceptive Electroreception and electrogenesis are the closely-related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes to stu ...

; although sensitive to electric charges, the fish does not possess an electric organ, but uses this ability to locate objects in its vicinity, detect prey, and avoid predators.

References

{{Taxonbar, from=Q387182 Notopteridae Freshwater fish of Africa Fish described in 1868 Taxa named by Albert Günther