RESEARCH STARTER

Lake Tanganyika

Lake Tanganyika is the second-deepest lake in the world, reaching depths of 4,823 feet (1,470 meters), and is located in the East African Great Rift Valley, straddling four countries: Burundi, the Democratic Republic of the Congo (DRC), Tanzania, and Zambia. Covering an area of approximately 12,703 square miles (32,900 square kilometers), it serves as a crucial ecological and economic resource for the estimated 10 million people living in its basin. The lake is known for its rich biodiversity, particularly its unique cichlid fish species, with over 250 cichlid species and high levels of endemism.

Lake Tanganyika's hydrology is largely influenced by rainfall and evaporation, with a very slow flushing time of up to 7,000 years, leading to distinct stratification of its waters. This meromictic nature means that the deeper layers of water do not mix with the surface waters, impacting nutrient availability and aquatic life. The lake is also vital for local fisheries, providing a significant protein source for the surrounding communities, though fish populations are currently threatened by climate change and unsustainable fishing practices.

In addition to fisheries, Lake Tanganyika supports agriculture, transport, and mining industries, but is facing environmental challenges including deforestation, erosion, and pollution from artisanal mining. Climate change has resulted in increased water temperatures and rising lake levels, causing displacement for many communities along its shores.

Full Article

  • Category: Inland Aquatic Biomes.
  • Geographic Location: Africa.
  • Summary: Lake Tanganyika is the world’s second-deepest freshwater lake and supports an amazing variety of fish species.

Lake Tanganyika is the second-deepest lake in the world, at 4,823 feet (1,470 meters), after Lake Baikal in Siberia. It is also the second-largest freshwater lake in the world by volume. It is located within the East African Great Rift Valley and is divided among four countries: Burundi, the Democratic Republic of the Congo (DRC), Tanzania, and Zambia. Most of the lake is within the DRC (45 percent) and Tanzania (41 percent). The water of the lake flows into the Congo River system and ultimately into the Atlantic Ocean.

Lake Tanganyika is narrow; it extends about 418 miles (673 kilometers) in length by 31 miles (50 kilometers) wide, on average. It covers 12,703 square miles (32,900 square kilometers), with a shoreline of 1,136 miles (1,828 kilometers), a mean depth of 1,870 feet (570 meters), and a maximum depth of 4,823 feet (1,470 meters) in the northern basin. It holds an estimated 4,530 cubic miles (18,900 cubic kilometers) of water.

The lake has an average surface temperature of 77 degrees F (25 degrees C) and a pH averaging 8.4, certainly a bit on the alkaline side. Studies show that beneath the 1,640 feet (500 meters) of water are about 14,764 feet (4,500 meters) of sediment lying over the rock floor.

Setting and Hydrology

The lake catchment is approximately 89,190 square miles (231,000 square kilometers), with the Ruzizi River, sometimes spelled Rusizi, entering from Lake Kivu in the north and the Malagarasi River entering from the east side of the lake; the catchment also includes many smaller streams and rivers. 

The lake is surrounded by mountainous areas. The eastern side has poorly developed coastal plains; on the western coast, the steep side walls of the Great Rift Valley reach 6,562 feet (2,000 meters) in relative height from the shoreline. Its sole effluent river, the Lukuga, starts from the middle part of the western coast and flows westward to join the Lualaba, a tributary of the Congo River, which flows on to the South Atlantic Ocean.

Due to the lake’s enormous depth and location within the tropics, there is little or no mixing of the shallower and deeper waters, which qualifies the lake as meromictic: the noncirculating bottom layer, or hypolimnion, does not merge with the upper layer, which is the circulating epilimnion. This combined oxygenated layer stretches to about 164–820 feet (50–250 meters), influenced by the seasons. The distribution of aquatic life is limited to this depth, since below this level the lake becomes anaerobic. In addition, the water becomes increasingly denser from all the accumulated particulate matter. As a result of this permanent stratification, most of the nutrients are stuck in the noncirculating hypolimnion.

Biodiversity

The lake has some of the richest lake fauna on Earth and is a critical biological resource used to study speciation in the evolutionary process. The lake’s great depth is thought to have given its fauna an evolutionary advantage. Over its long history, estimated at 9 million to 12 million years, Lake Tanganyika could have provided refuge for many aquatic organisms when other water bodies desiccated during extremely dry periods.

During low lake levels, the lake splits into two or three separate basins; this seems to have critically influenced the evolution of fishes, their diversity, and their distribution, facilitating allopatric speciation. The age of the lake has also facilitated further differentiation of the fish fauna compared with the fauna of lakes Malawi and Victoria. The Lake Tanganyika cichlids, for example, are believed to have descended from eight distinct ancestral lineages, more than in Lake Malawi or Lake Victoria.

The lake’s biodiversity exhibits high levels of endemism (species found exclusively here) within several taxonomic groups at the species and genus levels. It holds at least 150 non-cichlid species and 250 species of cichlid fish; a majority of these live along the shoreline to a depth of approximately 591 feet (180 meters).

Lake Tanganyika’s fish fauna shows close similarities with the Congo Basin, and the two systems are still connected hydrologically. In the late Miocene–early Pliocene, a large internal lake covering the Cuvette Centrale was part of the Congo basin.

It is believed that Lake Tanganyika’s fauna originated in this primitive environment; however, the timeline and details are incomplete. The Congo Basin fauna includes Lake Tanganyika’s twenty-three fish families.

Human Activities

It is estimated that the lake fish provides 60 percent of the dietary protein of the 10 million people who live around the lake. Fishery products, especially the Tanganyika sardine (Stolothrissa tanganicae), are vital for the local economy. More than 100,000 people, operating from nearly 800 sites, are involved in the fisheries. The lake is equally critical to the more than 10 million people living in the greater basin area.

Lake Tanganyika fish are exported throughout eastern Africa. Commercial fishing originated in the mid-1950s, and this practice has had a significant impact on pelagic fish species. In the mid-2010s, the total annual catch was about 200,000 tons (181,000 metric tons). However, the lake’s fish production has since begun a rapid decline, mostly due to climate change, warming waters, and overfishing, possibly due to the movement of refugees caused by regional conflicts in Burundi, the Democratic Republic of the Congo, and Rwanda. In September 2025, scientists initiated the first comprehensive fish stock assessment of Lake Tanganyika in nearly three decades to evaluate key pelagic species and support improved fisheries management.

The lake also serves as a transport gateway to the larger East Africa region. As an integral part of the region’s inland traffic system, regular shipping lines connect Kigoma, Tanzania, Kalemie, Democratic Republic of the Congo, and other coastal towns. Two passenger- and cargo-carrying ferries operate along the lake’s eastern shore: the MV Mwongozo, between Kigoma and Bujumbura, and the MV Liemba, between Kigoma and Mpulungu.

Agriculture, livestock, and the processing of their related products, as well as mining (tin, copper, and coal, mainly), are still the main industries in the drainage basin of Lake Tanganyika. Funded by the Global Environment Facility (GEF), in February 2025, Burundi, Tanzania, Zambia, and the Democratic Republic of the Congo launched a five-year environmental protection initiative for the Lake Tanganyika Basin with the intention of addressing biodiversity loss, unsustainable fisheries, and land degradation.

Environmental Threats

Some of the major environmental threats are deforestation, resulting from agricultural expansion, and overgrazing due to an influx of livestock, mostly from Sukuma people's land in Tanzania. These activities have led to increased erosion, causing more flooding in coastal areas and the siltation of the lake. There are also destructive fishing practices; the use of beach seines is rampant, especially in the inshore areas of the lake.

Artisanal, small-scale gold mining is another challenge to the lake ecosystem, particularly the use of mercury for binding the gold. In many cases, mercury residues escape to pollute the rivers used by the miners to process their gold, not to mention the neurotoxic effects of mercury on the miners themselves.

Climate change impacts on Lake Tanganyika have been the subject of numerous studies. The lake’s waters are warming, rising by about 2.3 degrees Fahrenheit (1.3 Celsius) from 1913 to the mid-2010s. Warmer water is lighter and limits the mixing of colder, deeper waters with surface waters. This, in turn, lessens the amount of nutrients that can churn up to the surface, reducing the prime food supply for the lake’s fish. On 23 April 2024, Lake Tanganyika reached a record height of 777.2 meters. Heavy rains caused the lake to overflow, resulting in massive floods. These floods displaced thousands of people in Burundi, including those in Bujumbura and other coastal towns. In May 2025, severe flooding triggered by torrential rains along the eastern shore of Lake Tanganyika in the Democratic Republic of the Congo killed at least 62 people and left dozens missing after villages were swept away.


Bibliography

Cohen, Andrew. “Lake Tanganyika Is Changing, and the Fate of Millions Lie in the Balance.” CNN, 18 May 2017, www.cnn.com/2017/05/18/africa/lake-tanganyika-under-threat-the-conversation. Accessed 12 Mar. 2026.

Concept Project Information Document/Integrated Safeguards Data Sheet Lake Tanganyika Environmental Management Project (P165749). World Bank, 5 Oct. 2018, documents1.worldbank.org/curated/en/668911539594000200/pdf/Concept-Project-Information-Document-Integrated-Safeguards-Data-Sheet-Lake-Tanganyika-Environmental-Management-Project-P165749.pdf. Accessed 12 Mar. 2026.

Coulter, G. W. Lake Tanganyika and Its Life. Oxford UP, 1991.

“First Fish Stock Assessment in 30 Years Underway on Lake Tanganyika.” FISH4ACP, Food and Agriculture Organization of the United Nations, 23 Sept. 2025, www.fao.org/fish4acp/media-hub/news/news-detail/first-fish-stock-assessment-in-30-years-underway-on-lake-tanganyika/en. Accessed 12 Mar. 2026.

Kiley, Sam. “Floods Force 100,000 out of Their Homes – and the Water in This African City Is Still Rising.” The Independent, 22 Sept. 2025, www.independent.co.uk/news/world/africa/burundi-flood-tanganyika-refugees-climate-war-b2802797.html. Accessed 12 Mar. 2026.

“Lake Tanganyika Basin Countries Launch Initiative to Protect Biodiversity, Halt Land Degradation.” Press Releases, 26 Feb. 2025, content.unops.org/documents/libraries/press-releases/2025/en/Press-release-Lake-Tanganika-basin-countries-launch-initiative-to-protect-biodiversity-and-degradation.pdf. Accessed 12 Mar. 2026.

“Lake Tanganyika Basin Countries Launch Initiative to Protect Biodiversity, Halt Land Degradation.” UN Environment Programme, 26 Feb. 2025, www.unep.org/gef/news-and-stories/press-release/lake-tanganyika-basin-countries-launch-initiative-protect. Accessed 12 Mar. 2026.

“Lake Tanganyika.” Living Lakes, livinglakes.org/lake-tanganyika/. Accessed 12 Mar. 2026.

“Lake Tanganyika Reaches Record Levels, Submerging Parts of Burundi.” African Arguments, 1 May 2024, africanarguments.org/2024/05/lake-tanganyika-reaches-record-levels-submerging-parts-of-burundi-floods/. Accessed 12 Mar. 2026.

Lowe-McConnell, Rosemary H. “Fish Faunas of the African Great Lakes: Origins, Diversity and Vulnerability.” Conservation Biology, vol. 7, 1993.

Patterson, G., and J. Makin. The State of Biodiversity in Lake Tanganyika: A Literature Review. Natural Resources Institute, 1998.

Paul, Madhumita. “Most Internal Displacement in East Africa’s Burundi Due to Rise of Lake Tanganyika.” Down to Earth, 20 Sept. 2021, www.downtoearth.org.in/news/climate-change/most-internal-displacement-in-east-africa-s-burundi-due-to-rise-of-lake-tanganyika-79106. Accessed 12 Mar. 2026.

“Restoring Balance to Lake Tanganyika.” The Nature Conservancy, 18 Sept. 2024, www.nature.org/en-us/about-us/where-we-work/africa/stories-in-africa/lake-tanganyika-basin/. Accessed 12 Mar. 2026.

Roberts, T. R. “Geographical Distribution of African Freshwater Fishes.” Zoological Journal of the Linnean Society, vol. 57, 1975.

Salzburger, W., et al. “Phylogeny of the Lake Tanganyika Cichlid Species Flock and Its Relationship to the Central and East African Haplochromine Cichlid Fish Faunas.” Systematic Biology, vol. 51, no. 1, 2002.

Full Article

  • Category: Inland Aquatic Biomes.
  • Geographic Location: Africa.
  • Summary: Lake Tanganyika is the world’s second-deepest freshwater lake and supports an amazing variety of fish species.

Lake Tanganyika is the second-deepest lake in the world, at 4,823 feet (1,470 meters), after Lake Baikal in Siberia. It is also the second-largest freshwater lake in the world by volume. It is located within the East African Great Rift Valley and is divided among four countries: Burundi, the Democratic Republic of the Congo (DRC), Tanzania, and Zambia. Most of the lake is within the DRC (45 percent) and Tanzania (41 percent). The water of the lake flows into the Congo River system and ultimately into the Atlantic Ocean.

Lake Tanganyika is narrow; it extends about 418 miles (673 kilometers) in length by 31 miles (50 kilometers) wide, on average. It covers 12,703 square miles (32,900 square kilometers), with a shoreline of 1,136 miles (1,828 kilometers), a mean depth of 1,870 feet (570 meters), and a maximum depth of 4,823 feet (1,470 meters) in the northern basin. It holds an estimated 4,530 cubic miles (18,900 cubic kilometers) of water.

The lake has an average surface temperature of 77 degrees F (25 degrees C) and a pH averaging 8.4, certainly a bit on the alkaline side. Studies show that beneath the 1,640 feet (500 meters) of water are about 14,764 feet (4,500 meters) of sediment lying over the rock floor.

Setting and Hydrology

The lake catchment is approximately 89,190 square miles (231,000 square kilometers), with the Ruzizi River, sometimes spelled Rusizi, entering from Lake Kivu in the north and the Malagarasi River entering from the east side of the lake; the catchment also includes many smaller streams and rivers. 

The lake is surrounded by mountainous areas. The eastern side has poorly developed coastal plains; on the western coast, the steep side walls of the Great Rift Valley reach 6,562 feet (2,000 meters) in relative height from the shoreline. Its sole effluent river, the Lukuga, starts from the middle part of the western coast and flows westward to join the Lualaba, a tributary of the Congo River, which flows on to the South Atlantic Ocean.

Due to the lake’s enormous depth and location within the tropics, there is little or no mixing of the shallower and deeper waters, which qualifies the lake as meromictic: the noncirculating bottom layer, or hypolimnion, does not merge with the upper layer, which is the circulating epilimnion. This combined oxygenated layer stretches to about 164–820 feet (50–250 meters), influenced by the seasons. The distribution of aquatic life is limited to this depth, since below this level the lake becomes anaerobic. In addition, the water becomes increasingly denser from all the accumulated particulate matter. As a result of this permanent stratification, most of the nutrients are stuck in the noncirculating hypolimnion.

Biodiversity

The lake has some of the richest lake fauna on Earth and is a critical biological resource used to study speciation in the evolutionary process. The lake’s great depth is thought to have given its fauna an evolutionary advantage. Over its long history, estimated at 9 million to 12 million years, Lake Tanganyika could have provided refuge for many aquatic organisms when other water bodies desiccated during extremely dry periods.

During low lake levels, the lake splits into two or three separate basins; this seems to have critically influenced the evolution of fishes, their diversity, and their distribution, facilitating allopatric speciation. The age of the lake has also facilitated further differentiation of the fish fauna compared with the fauna of lakes Malawi and Victoria. The Lake Tanganyika cichlids, for example, are believed to have descended from eight distinct ancestral lineages, more than in Lake Malawi or Lake Victoria.

The lake’s biodiversity exhibits high levels of endemism (species found exclusively here) within several taxonomic groups at the species and genus levels. It holds at least 150 non-cichlid species and 250 species of cichlid fish; a majority of these live along the shoreline to a depth of approximately 591 feet (180 meters).

Lake Tanganyika’s fish fauna shows close similarities with the Congo Basin, and the two systems are still connected hydrologically. In the late Miocene–early Pliocene, a large internal lake covering the Cuvette Centrale was part of the Congo basin.

It is believed that Lake Tanganyika’s fauna originated in this primitive environment; however, the timeline and details are incomplete. The Congo Basin fauna includes Lake Tanganyika’s twenty-three fish families.

Human Activities

It is estimated that the lake fish provides 60 percent of the dietary protein of the 10 million people who live around the lake. Fishery products, especially the Tanganyika sardine (Stolothrissa tanganicae), are vital for the local economy. More than 100,000 people, operating from nearly 800 sites, are involved in the fisheries. The lake is equally critical to the more than 10 million people living in the greater basin area.

Lake Tanganyika fish are exported throughout eastern Africa. Commercial fishing originated in the mid-1950s, and this practice has had a significant impact on pelagic fish species. In the mid-2010s, the total annual catch was about 200,000 tons (181,000 metric tons). However, the lake’s fish production has since begun a rapid decline, mostly due to climate change, warming waters, and overfishing, possibly due to the movement of refugees caused by regional conflicts in Burundi, the Democratic Republic of the Congo, and Rwanda. In September 2025, scientists initiated the first comprehensive fish stock assessment of Lake Tanganyika in nearly three decades to evaluate key pelagic species and support improved fisheries management.

The lake also serves as a transport gateway to the larger East Africa region. As an integral part of the region’s inland traffic system, regular shipping lines connect Kigoma, Tanzania, Kalemie, Democratic Republic of the Congo, and other coastal towns. Two passenger- and cargo-carrying ferries operate along the lake’s eastern shore: the MV Mwongozo, between Kigoma and Bujumbura, and the MV Liemba, between Kigoma and Mpulungu.

Agriculture, livestock, and the processing of their related products, as well as mining (tin, copper, and coal, mainly), are still the main industries in the drainage basin of Lake Tanganyika. Funded by the Global Environment Facility (GEF), in February 2025, Burundi, Tanzania, Zambia, and the Democratic Republic of the Congo launched a five-year environmental protection initiative for the Lake Tanganyika Basin with the intention of addressing biodiversity loss, unsustainable fisheries, and land degradation.

Environmental Threats

Some of the major environmental threats are deforestation, resulting from agricultural expansion, and overgrazing due to an influx of livestock, mostly from Sukuma people's land in Tanzania. These activities have led to increased erosion, causing more flooding in coastal areas and the siltation of the lake. There are also destructive fishing practices; the use of beach seines is rampant, especially in the inshore areas of the lake.

Artisanal, small-scale gold mining is another challenge to the lake ecosystem, particularly the use of mercury for binding the gold. In many cases, mercury residues escape to pollute the rivers used by the miners to process their gold, not to mention the neurotoxic effects of mercury on the miners themselves.

Climate change impacts on Lake Tanganyika have been the subject of numerous studies. The lake’s waters are warming, rising by about 2.3 degrees Fahrenheit (1.3 Celsius) from 1913 to the mid-2010s. Warmer water is lighter and limits the mixing of colder, deeper waters with surface waters. This, in turn, lessens the amount of nutrients that can churn up to the surface, reducing the prime food supply for the lake’s fish. On 23 April 2024, Lake Tanganyika reached a record height of 777.2 meters. Heavy rains caused the lake to overflow, resulting in massive floods. These floods displaced thousands of people in Burundi, including those in Bujumbura and other coastal towns. In May 2025, severe flooding triggered by torrential rains along the eastern shore of Lake Tanganyika in the Democratic Republic of the Congo killed at least 62 people and left dozens missing after villages were swept away.


Bibliography

Cohen, Andrew. “Lake Tanganyika Is Changing, and the Fate of Millions Lie in the Balance.” CNN, 18 May 2017, www.cnn.com/2017/05/18/africa/lake-tanganyika-under-threat-the-conversation. Accessed 12 Mar. 2026.

Concept Project Information Document/Integrated Safeguards Data Sheet Lake Tanganyika Environmental Management Project (P165749). World Bank, 5 Oct. 2018, documents1.worldbank.org/curated/en/668911539594000200/pdf/Concept-Project-Information-Document-Integrated-Safeguards-Data-Sheet-Lake-Tanganyika-Environmental-Management-Project-P165749.pdf. Accessed 12 Mar. 2026.

Coulter, G. W. Lake Tanganyika and Its Life. Oxford UP, 1991.

“First Fish Stock Assessment in 30 Years Underway on Lake Tanganyika.” FISH4ACP, Food and Agriculture Organization of the United Nations, 23 Sept. 2025, www.fao.org/fish4acp/media-hub/news/news-detail/first-fish-stock-assessment-in-30-years-underway-on-lake-tanganyika/en. Accessed 12 Mar. 2026.

Kiley, Sam. “Floods Force 100,000 out of Their Homes – and the Water in This African City Is Still Rising.” The Independent, 22 Sept. 2025, www.independent.co.uk/news/world/africa/burundi-flood-tanganyika-refugees-climate-war-b2802797.html. Accessed 12 Mar. 2026.

“Lake Tanganyika Basin Countries Launch Initiative to Protect Biodiversity, Halt Land Degradation.” Press Releases, 26 Feb. 2025, content.unops.org/documents/libraries/press-releases/2025/en/Press-release-Lake-Tanganika-basin-countries-launch-initiative-to-protect-biodiversity-and-degradation.pdf. Accessed 12 Mar. 2026.

“Lake Tanganyika Basin Countries Launch Initiative to Protect Biodiversity, Halt Land Degradation.” UN Environment Programme, 26 Feb. 2025, www.unep.org/gef/news-and-stories/press-release/lake-tanganyika-basin-countries-launch-initiative-protect. Accessed 12 Mar. 2026.

“Lake Tanganyika.” Living Lakes, livinglakes.org/lake-tanganyika/. Accessed 12 Mar. 2026.

“Lake Tanganyika Reaches Record Levels, Submerging Parts of Burundi.” African Arguments, 1 May 2024, africanarguments.org/2024/05/lake-tanganyika-reaches-record-levels-submerging-parts-of-burundi-floods/. Accessed 12 Mar. 2026.

Lowe-McConnell, Rosemary H. “Fish Faunas of the African Great Lakes: Origins, Diversity and Vulnerability.” Conservation Biology, vol. 7, 1993.

Patterson, G., and J. Makin. The State of Biodiversity in Lake Tanganyika: A Literature Review. Natural Resources Institute, 1998.

Paul, Madhumita. “Most Internal Displacement in East Africa’s Burundi Due to Rise of Lake Tanganyika.” Down to Earth, 20 Sept. 2021, www.downtoearth.org.in/news/climate-change/most-internal-displacement-in-east-africa-s-burundi-due-to-rise-of-lake-tanganyika-79106. Accessed 12 Mar. 2026.

“Restoring Balance to Lake Tanganyika.” The Nature Conservancy, 18 Sept. 2024, www.nature.org/en-us/about-us/where-we-work/africa/stories-in-africa/lake-tanganyika-basin/. Accessed 12 Mar. 2026.

Roberts, T. R. “Geographical Distribution of African Freshwater Fishes.” Zoological Journal of the Linnean Society, vol. 57, 1975.

Salzburger, W., et al. “Phylogeny of the Lake Tanganyika Cichlid Species Flock and Its Relationship to the Central and East African Haplochromine Cichlid Fish Faunas.” Systematic Biology, vol. 51, no. 1, 2002.

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