The Niger & Volta

The Niger and the Volta are West Africa's two great river systems, and between them they water the savanna heart of the region from the Atlantic to the edge of the Sahara. The Niger is the continent's third-longest river — roughly 2,600 miles (about 4,124 mi) — looping in a vast boomerang arc out of the Guinea highlands, north toward Timbuktu, then southeast through Niger and Nigeria to the sea. Along the way it does something no other river its size does so dramatically: it spreads into the Inner Niger Delta, an inland flood-sea of up to 11,500 square miles (30,0 mi²) in the parched middle of Mali, before finally pouring out through the mangrove-laced Niger Delta on the Gulf of Guinea. The Volta, smaller but no less consequential, gathers its Black, White and Red branches across Burkina Faso and Ghana and ends in Lake Volta, the largest reservoir on Earth by surface area, held back by the Akosombo Dam. These are warm, seasonally flooded, savanna-and-forest rivers, and their cichlids — tilapias, jewel cichlids and the rainbow kribs — are the West African counterweight to the famous flocks of the Rift lakes: fewer species, but the wild ancestors of some of the most familiar fish in the hobby.

Setting & origin

The Niger rises only about 150 miles (149 mi) from the Atlantic in the Fouta Djallon highlands of Guinea, yet rather than running straight to the nearby coast it strikes out inland to the northeast, in a course so counterintuitive that early geographers could not agree on where it went. It is Africa's third-longest river after the Nile and the Congo, about 2,600 miles (4,124 mi) long, draining roughly 730,000 square miles (about 1,900,0 mi²) across West Africa (Britannica; FAO). Two features define it. The first is the Inner Niger Delta in Mali — not a true delta but a vast inland floodplain where the Niger and its great tributary the Bani slow, braid and spill out across a flat basin, inundating up to about 11,500 square miles (30,0 mi²) at the flood peak and losing roughly half their combined water to evaporation and seepage before the river reconvenes and bends past Timbuktu toward the desert's edge (Brunet-Moret; FAO; Ramsar). The second is the true Niger Delta in Nigeria, an enormous arc of distributary creeks, swamp forest and mangrove — on the order of 14,000 square miles (about 36,0 mi²) — where the river finally meets the Gulf of Guinea.

The Volta system is smaller and entirely savanna-to-forest in character. Its three named branches — the Black Volta (a permanent river rising near the Burkina Faso–Mali borderlands), and the seasonal White Volta and Red Volta, which run dry for months in northern Burkina Faso — converge in Ghana and feed Lake Volta, the reservoir impounded since the mid-1960s behind the Akosombo Dam. By surface area, around 3,280 square miles (about 8,311 mi²), Lake Volta is the largest artificial lake on the planet (Britannica; FEOW).

Both basins are profoundly transboundary. The Niger is shared by nine states — Guinea, Mali, Niger, Benin, Nigeria, plus Burkina Faso, Côte d'Ivoire, Cameroon and Chad in its wider catchment — coordinated, on paper, through the Niger Basin Authority (NBA/ABN). The Volta spans six — chiefly Burkina Faso and Ghana, with Benin, Côte d'Ivoire, Mali and Togo — and is overseen by the Volta Basin Authority. Nigeria, Mali, Niger, Ghana, Burkina Faso, Guinea, Benin and Côte d'Ivoire are the principal riparian nations whose people live by these waters.

Temperature & flow

These are warm tropical rivers, and unlike the deep Rift lakes they have essentially no permanent thermal layering — they are shallow, flowing and well mixed, so a single water temperature describes most of the column at any given time and place. Across the savanna reaches and the floodplains, water temperatures typically sit in the mid-70s to upper 80s °F (about 75–88 °F), tracking the air and the season; the wild habitats of the Niger Delta kribs are reported around 75–79 °F (75–79 °F), while open floodplain water in the hot Sahelian months runs warmer still. There is no cold deep layer to speak of — the relevant figure here is not a thermocline but the flood.

Flow is everything. Both systems are driven by a single annual monsoon pulse: a long dry season followed by summer rains that send a flood wave down the river months later. In the Inner Niger Delta the flood arriving from the Guinea highlands swells the river from late summer, peaks around September–November, and floods the basin out to its tens of thousands of square kilometers before draining away into the dry season — a classic flood-pulse system in which the rise and fall of the water, not temperature, sets the biological calendar (Ramsar; FAO). The same monsoon rhythm fills the seasonal White and Red Volta, which can cease to flow entirely in the dry months. This strong seasonality means discharge and flooded area swing enormously year to year, and the fish — like the fisheries — are tuned to time their breeding and feeding to the rising water.

Water chemistry & clarity

Chemically these are soft, lightly mineralized savanna rivers — a different world from the alkaline, high-conductivity Rift lakes. In the Inner Niger Delta, the Niger and Bani carry low dissolved-ion loads: conductivity is reported on the order of 50–80 µS/cm, rising during the low-water stage as the shrinking water concentrates and dropping sharply as the flood dilutes it (Brunet-Moret/researchers on the inner-delta water balance). pH runs near neutral to mildly alkaline in the open river — broadly in the 7–8 range in the inner delta — but in the tannin-stained, vegetation-choked creeks of the forested lower Niger Delta it tips acidic and very soft: the wild kribensis streams there are described as pH ~5.6–6.2 with hardness of only about 12–22 mg/L CaCO₃. That softness and acidity is exactly why West African cichlids are kept so differently from their hard-water Rift cousins.

Clarity is governed by flood and sediment rather than by plankton. During the rising flood the rivers run turbid and brown with suspended silt; as the water clears and recedes, floodplain lakes can become quite transparent before the next pulse. Toward the coast, the lower Niger Delta is genuinely brackish: an estuarine gradient of tidal mangrove channels where salinity climbs toward the sea, and where the resident cichlids are salt-tolerant species rather than strict freshwater forms. So a single basin spans the full chemical range — soft savanna river, tannic forest creek, and brackish mangrove estuary.

Habitats

Four broad habitat worlds give these basins their character. The first is the open Sahelian river — wide, sandy- and muddy-bedded main channels running through dry savanna, with sandbars, vegetated margins and rocky rapids where rheophilic (current-loving) species cling to the stones. The second is the inland-delta floodplain of Mali: a seasonally drowned mosaic of channels, shallow lakes (the local maa-yos and lakes around Mopti and Timbuktu) and flooded grassland that, at peak, becomes one of the largest wetlands in Africa and a Ramsar site of global importance. It is a nursery on a continental scale — fish surge out across the flooded plain to feed and spawn, then crowd back into the channels as the water falls.

The third is the Niger Delta of Nigeria, grading from freshwater swamp forest inland to a coastal belt of mangroves and tidal creeks — brackish, sheltered, root-tangled habitat that is home to the salt-tolerant tilapias and to the rainbow kribs in its fresher, vegetated reaches. The forested creeks here are soft, acidic, shaded and full of leaf litter and submerged plants — small-cichlid country par excellence. The fourth is wholly artificial: Lake Volta and the other big West African reservoirs (Kainji on the Niger, among others), where a flowing river has been turned into standing water. These lakes drowned former floodplains and rapids, swapped riverine fish for lake-adapted ones, and now host the open-water tilapia fisheries that feed much of Ghana and Nigeria.

The cichlids

The Niger and Volta share the broad West African (Nilo-Sudanian and Guinean) cichlid fauna — far fewer species than a Rift lake, but a roster that any aquarist will recognize, because so many hobby staples are West African river fish. The backbone is the tilapias, the substrate-spawning and mouthbrooding cichlids that anchor the food fishery: Coptodon zillii (the redbelly tilapia, long known as Tilapia zillii) and Coptodon guineensis; the mouthbrooding Sarotherodon galilaeus and the brackish-tolerant Sarotherodon melanotheron (the blackchin tilapia of the delta mangroves); and Oreochromis niloticus, the Nile tilapia, native here and now the most-farmed cichlid on Earth. Tilapia guineensis and Tilapia dageti round out the larger tilapiine guild.

Then come the jewel cichlids, Hemichromis — the fierce, blood-red H. bimaculatus group and the larger banded predator H. fasciatus — pugnacious biparental spawners found throughout both systems. And the gems of the West African scene are the dwarf and medium cichlids of the forest waters: the rainbow kribs, Pelvicachromis, whose best-known member, P. pulcher, the common krib, was described in 1901 from the Niger Delta itself — its type locality the Ethiope River drainage — and went on to become one of the most popular aquarium cichlids in the world. Alongside the kribs are the mouthbrooding Chromidotilapia (such as C. guentheri), the vegetation-loving Thysochromis, several smaller Tilapia-group species, and the rheophilic Steatocranus irvinei clinging to the Volta rapids — the latter one of the Volta basin's few endemics. The combined Niger–Volta cichlid fauna runs to roughly 30–40 species: modest beside Malawi's hundreds, but a fauna of broad, hardy, widely distributed river fish, several of which underpin both the dinner table and the home aquarium across the tropics.

People & pressures

Few freshwater systems feed more people. The Inner Niger Delta alone supports on the order of two million people through fishing, flood-recession farming and cattle herding, and produces the great majority of Mali's fish — an inland catch historically near 100,000 tons a year and, for decades, a sizable share of the national economy (World Water Week/Mali fisheries; FAO). Lake Volta carries one of Africa's largest reservoir fisheries, with hundreds of thousands of fisherfolk and the lake supplying around 90% of Ghana's inland fish; Kainji Lake and the lower Niger do the same for Nigeria. Across the two basins, tens of millions of people draw protein and livelihood directly from the water.

The pressures are heavy and distinctly West African. Big dams reshaped both rivers: Akosombo created Lake Volta but also cut the flood and sediment that once renewed the lower Volta and its coast, while Kainji and other Niger barrages altered flow downstream — a recurring tension between hydropower and the flood pulse the fisheries depend on. In the Niger Delta of Nigeria, decades of oil extraction have left a grim legacy of spills and chronic contamination; oil in the mangrove soils is re-released with each tidal inundation, fish populations have been depleted, and a meaningful fraction of the delta's mangroves has been lost to pollution and clearance (Mongabay; PLOS ONE). The Sahel's recurring droughts shrink the inner-delta flood and squeeze its fishery; upstream irrigation and proposed dams threaten to shrink it further. And across the region the floating water hyacinth (Eichhornia crassipes), an introduced South American weed, now chokes creeks and reservoirs from the Niger Delta to Lake Volta, smothering open water, deoxygenating it and fouling the very fishing grounds these communities depend on. Managing all of it across so many borders is the standing task of the Niger and Volta basin authorities — and, so far, an unfinished one.

Sources

Last reviewed 2026-06-06.

How to cite

Aquarist Atlas (2026). The Niger & Volta. Aquarist Atlas. https://www.aquaristatlas.com/water/niger-volta/

Setting & origin

Temperature & flow

Water chemistry & clarity

Habitats

The cichlids

People & pressures

Sources

Cichlids recorded here

Benitochromis

Chromidotilapia

Coptodon

Gobiocichla

Hemichromis

Oreochromis

Paragobiocichla

Parananochromis

Pelmatolapia

Pelvicachromis

Rubricatochromis

Sarotherodon

Stomatepia

Thysochromis

Tylochromis