Where in the world: The River Niger

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The Niger is home to some 200 species and many are encountered as aquarium fish, as Dr Heok Hee Ng explains...

The Niger is the principal river draining West Africa, being some 4,180km/2,598 miles long and draining 2,117,700  square km/817,380 square miles. With its headwaters in Guinea, the river runs a boomerang-shaped course through Mali, Niger, Benin and Nigeria before discharging into the Gulf of Guinea.

Pufferfishes

Only one species of freshwater pufferfish — the Fahaka puffer (Tetraodon lineatus) pictured above — is found in this river drainage.

This very aggressive puffer species is best kept in a species tank, especially since specimens are capable of reaching slightly over 40cm/16” when fully grown.

Lungfishes

The Niger is home to a single species of African lungfish, Protopterus annectens. This fish can grow up to 1m /39” in length and is highly predatory in nature. For that very reason, it is best kept in a species-only tank.

Lungfishes are fairly tolerant of a wide range of water conditions.

Electric fishes

Twenty-nine species of electric fishes are known from the Niger river drainage. This includes 28 species of the weakly electric mormyrids and Aba Aba (Gymnarchus niloticus). Some mormyrid species found here, such as Gnathonemus petersii, are among the most commonly encountered in the aquarium trade.

Bichirs

Four species of bichirs (Polypterus) and one of reedfish (Erpetoichthys) are known from the drainage: Polypterus ansorgii, P. bichir, P. endlicheri, P. senegalus and Erpetoichthys calabaricus.  The bichirs of this river system are perhaps the least colourful of the family, but probably the most commonly available aquarium fish.

Tetras

Although the characiform (tetra) fauna of the Niger drainage is not high, a fairly high proportion are in the trade. Many are small to medium-sized species, such as Arnoldichthys spilopterus, Nannaethiops unitaeniatus and Neolebias ansorgii, although juveniles of the large, predatory tigerfishes (Hydrocynus spp.) have also been offered for sale.

Bony tongues

Non-electrogenic osteoglossiform or bony-tongue species include the African bonytongue (Heterotis niloticus), Butterflyfish (Pantodon buchholzi) and two species of notopterid knifefishes (Papyrocranus afer and Xenomystus nigri). The Butterflyfish is a surface hunter and should not be kept with other surface dwellers!

Barbs

West African members of the genus Barbus are not that colourful; the larger are plain silvery and the smaller ones have black spots or stripes. The genus is moderately diverse, encompassing 17 of the 26 cyprinid species, however, and the smaller species, such as Barbus eburneensis  have been encountered occasionally as aquarium fish.

Cichlids

Although only 16 species are known from the drainage, some of the more iconic species, such as Pelvicachromis pulcher and Hemichromis bimaculatus, hail from here. The cichlid fauna of this system is dominated by tilapiines (members of the genera Tilapia, Sarotherodon and Oreochromis) which make up half of all cichlids known from here.

Catfishes

The drainage is home to about 58 species, the most prominent being members of the family Mochokidae. Some of the most common Synodontis species in the trade, such as S. eupterus and S. nigrita, are from here. Many undescribed species also come from this system, prominent being a Microsynodontis frequently imported from Nigeria.

Killifishes

This group is very diverse, with some 20 species known from here, although many more undescribed species are present. The following genera have been recorded from the river system: Aphyosemion, Aplocheilichthys, Chromaphyosemion, Epiplatys, Fundulopanchax, Fundulosoma, Nothobranchius, Procatopus and Scriptaphyosemion.

Why not check out our other feature in this series: Where in the world: Thailand?