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

Notopteridae The family Notopteridae contains 11 species of osteoglossiform (bony-tongued) fishes, commonly known as featherbacks and knifefishes. These fishes live in freshwater or brackish environments in Africa and West, South, East and Southeast Asia. W ...

, the featherbacks, found in tropical

West Africa West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...

. 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 Niger, officially the Republic of the Niger, is a landlocked country in West Africa. It is a unitary state Geography of Niger#Political geography, bordered by Libya to the Libya–Niger border, north-east, Chad to the Chad–Niger border, east ...

basin and other coastal river basins including the Tano River and Pra River basins in Ghana, and the Cross River and Sanaga River 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 geopolitic ...

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 in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

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 a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

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 (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...

fish to be electroreceptive; 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