Niger basin

The blue diamond tetra, Alestopetersius smykalai, is an alestid from the Imo and Niger drainages in Nigeria. The only member of its genus found outside the Congo system, it has a prominent dark, roughly diamond-shaped marking on the caudal peduncle, and adult males lack extended median caudal-fin rays. Very rare in the hobby, it is considered Vulnerable by the IUCN because of rainforest loss, dams and habitat degradation in the Niger delta.

The African red-eyed tetra, Arnoldichthys spilopterus, is a characin endemic to Nigeria, where it occurs in the Ogun and lower Niger river systems. Also known as the 'large-scaled African characin' or 'Niger tetra', it has large scales compared with most relatives and is hardy once settled. In the wild it is relatively scarce, known from fewer than 10 localities in an area of extensive deforestation and pollution.

'Barbus' sublineatus is a widespread West African barb found in river basins from Senegal east to Cameroon, including the Niger and Volta. It is very variable in patterning and can be difficult to identify: Upper Niger fish show three elongate midlateral markings, Middle Niger fish a continuous band and Volta fish four spots. It may prove to be a complex of closely-related species. Little is known of its captive care.

Chromidotilapia guntheri is a mouthbrooding cichlid from coastal drainages of western Africa between Liberia and Cameroon, plus the Niger and Benue. It occurs in a number of geographic forms, with fish from Cameroon tending to show dark blotches on the dorsal fin. A benthophagous omnivore, it sifts mouthfuls of substrate for food, and the male broods the eggs while the female defends the surrounding territory.

The red-spotted panchax, Epiplatys lamottei, is a killifish with a restricted range in southeastern Guinea and northern Liberia. Known from the upper Niger, Lofa, Saint Paul and Saint John drainages, it inhabits small streams and minor tributaries, and is threatened by deforestation and mining across some of its range. The flanks carry large dark bars and longitudinal bands made up of small red spots.

The six-barred panchax, Epiplatys sexfasciatus, is a killifish from coastal regions between Gabon and Ghana. Well established in the hobby in several forms, it has a confusing taxonomy, and some authors restrict it to northwestern Gabon and Equatorial Guinea and treat other populations as subspecies. It mostly inhabits freshwater swamps and minor tributary streams, and is relatively easy to breed.

Parachanna africana is an African snakehead found from Benin to Nigeria, in lowland coastal rivers draining into the Gulf of Guinea. Sometimes called the 'Niger snakehead', it is uncommon in the trade, and its name is sometimes misapplied to P. obscura. A series of 8-11 dark chevrons along the body identifies it, though these may not show depending on mood. It is best kept in a species-specific aquarium with a tight-fitting hood.

The two-striped lyretail, Aphyosemion bitaeniatum, is a killifish from lowland coastal regions of Togo, Benin and Nigeria. Its range reaches the Cross River delta and some inland localities along the lower Niger River. Populations in Cameroon, Equatorial Guinea and Gabon are now considered to represent other species.

The steel-blue killifish, Fundulopanchax gardneri, is native to the Cross River system in Nigeria and Cameroon and the Benue River drainage. Also known as Gardner's killi or blue lyretail, the common aquarium forms are among the best choices for those new to killifishes. Wild populations come in numerous colour forms, three of them described as subspecies. Its eggs can withstand a period of drying but will also hatch when kept submerged.

The Bouala lyretail, Aphyosemion bualanum, is a killifish from the upper Benue and Mayo Kébbi systems in Cameroon, Central African Republic and Chad. It is listed as endangered by the IUCN. Before 1990 the name was misused for various populations of A. elberti.