Lake Malawi, also known as Lake Nyasa in

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

and Lago Niassa in

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

, () is an African Great Lake and the southernmost lake in the

East African Rift The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a l ...

system, located between

Malawi Malawi, officially the Republic of Malawi, is a landlocked country in Southeastern Africa. It is bordered by Zambia to the west, Tanzania to the north and northeast, and Mozambique to the east, south, and southwest. Malawi spans over and ...

, Mozambique and Tanzania. It is the fourth largest freshwater lake in the world by volume, the ninth largest lake in the world by area and the third largest and second deepest lake in Africa. Lake Malawi is home to more species of fish than any other lake in the world, including at least 700 species of

cichlid Cichlids () are a large, diverse, and widespread family of percomorph fish in the family Cichlidae, order Cichliformes. At least 1,760 species have been scientifically described, making it one of the largest vertebrate families, with on ...

s.Turner, Seehausen, Knight, Allender, and Robinson (2001). "How many species of cichlid fishes are there in African lakes?" ''Molecular Ecology'' 10: 793–806. The Mozambique portion of the lake was officially declared a reserve by the Government of Mozambique on June 10, 2011,WWF (10 June 2011)
"Mozambique’s Lake Niassa declared reserve and Ramsar site"
Retrieved 17 July 2014. while in Malawi a portion of the lake is included in Lake Malawi National Park. Lake Malawi is a meromictic lake, meaning that its water layers do not mix. The permanent stratification of Lake Malawi's water and the oxic-

anoxic Anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts: * Anoxic waters, sea water, fresh water or groundwater that are depleted of dissolved ox ...

boundary are maintained by moderately small chemical and thermal gradients.

Geography

Lake Malawi is between and long, and about wide at its widest point. The lake has a total

surface area The surface area (symbol ''A'') of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the d ...

of about . The lake is at its deepest point, located in a major depression in the north-central part. Another smaller depression in the far north reaches a depth of . The southern half of the lake is shallower; less than in the south-central part and less than in the far south. The lake has shorelines on western

, eastern

, and southern

. The largest river flowing into it is the Ruhuhu River, and there is an outlet at its southern end, the Shire River, a tributary that flows into the

Zambezi River The Zambezi (also spelled Zambeze and Zambesi) is the fourth-longest river in Africa, the longest east-flowing river in Africa and the largest flowing into the Indian Ocean from Africa. Its drainage basin covers , slightly less than half of t ...

in Mozambique. Evaporation accounts for more than 80% of the water loss from the lake, considerably more than the outflowing Shire River.Park, L.E.; and A.S. Cohen (2011). Paleoecological response of ostracods to early Late Pleistocene lake-level changes in Lake Malawi, East Africa. Palaeogeography, Palaeoclimatology, Palaeoecology 303: 71–80. The outflows from Lake Malawi into the Shire River are vital for the economy as the water resources support hydropower, irrigation and downstream biodiversity. Concerns have been raised over the future climate change impacts of Lake Malawi due to the recent decline in lake levels and the overall drying trend. The climate in the lake region is already experiencing changes, with the temperatures predicted to increase throughout the country. The lake is about southeast of

Lake Tanganyika Lake Tanganyika ( ; ) is an African Great Lakes, African Great Lake. It is the world's List of lakes by volume, second-largest freshwater lake by volume and the List of lakes by depth, second deepest, in both cases after Lake Baikal in Siberia. ...

, another of the great lakes of the East African Rift. The Lake Malawi National Park is located at the southern end of the lake. File:Lake Malawi00.jpg, Lake Malawi (1967) File:Mwaya Beach, Malawi.jpg, Mwaya Beach File:Monoxylon beach Lake Malawi 1557.jpg, Beach at Cape Maclear near Monkey Bay

Geological history

Malawi is one of the major Rift Valley lakes and an

ancient lake An ancient lake is a lake that has consistently carried water for more than one million years. Twelve of the 20 ancient lakes have existed for more than 2.6 million years, the full Quaternary period. Ancient lakes continue to persist due to plat ...

. The lake lies in a valley formed by the opening of the

, where the African tectonic plate is being split into two pieces. This is called a divergent plate tectonics boundary. Malawi has typically been estimated to be 1–2 million years old (mya),Givnish, T.J.; and K.J. Sytsma, editors (1997). Molecular Evolution and Adaptive Radiation, p. 598. . but more recent evidence points to a considerably older lake with a basin that started to form about 8.6 mya and deep-water condition first appeared 4.5 mya.Delvaux, D. (1995). Age of Lake Malawi (Nyasa) and water level fluctuations. Mus. roy. Afr. centr., Tervuren (Belg.), Dept. Geol. Min., Rapp. ann. 1993 & 1994: 99–108.Sturmbauer; Baric; Salzburger; Rüber; and Verheyen (2001). Lake Level Fluctuations Synchronize Genetic Divergences of Cichlid Fishes in African Lakes. Mol Biol Evol 18(2): 144–154. The water levels have varied dramatically over time, ranging from almost below current levelCohen; Stone; Beuning; Park; Reinthal; Dettman; Scholz; Johnson; King; Talbot; Brown; and Ivory (2007). Ecological consequences of early Late Pleistocene megadroughts in tropical Africas. Proc Natl Acad Sci USA 104(42): 16422-16427. to above. During periods the lake dried out almost completely, leaving only one or two relatively small, highly

alkaline In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...

and saline lakes in what currently are Malawi's deepest parts. A water chemistry resembling the current conditions only appeared about 60,000 years ago. Major low-water periods are estimated to have occurred about 1.6 to 1.0–0.57 million years ago (where it might have dried out completely), 420,000 to 250,000–110,000 years ago, about 25,000 years ago and 18,000–10,700 years ago. During the peak of the low-water period between 1390 and 1860 AD, it may have been below current water levels.

Water characteristics

The lake's water is alkaline ( pH 7.7–8.6) and warm with a typical surface temperature between , while deep sections typically are about .Stauffer, J.R.; and H. Madsen (2012). Schistosomiasis in Lake Malawi and the Potential Use of Indigenous Fish for Biological Control. Pp. 119–140 in: Rokni, M.B., editor. Schistosomiasis. . The

thermocline A thermocline (also known as the thermal layer or the metalimnion in lakes) is a distinct layer based on temperature within a large body of fluid (e.g. water, as in an ocean or lake; or air, e.g. an atmosphere) with a high gradient of distinct te ...

is located at a depth of . The

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 ...

limit is at a depth of approximately , effectively restricting fish and other aerobic organisms to the upper part.Lowe-McConnell, R.H. (2003). Recent research in the African Great Lakes: Fisheries, biodiversity and cichlid evolution. Freshwater Forum 20(1): 4–64. The water is very clear for a lake and the visibility can be up to , but slightly less than half this figure is more common and it is below in muddy bays. Konings, Ad (1990). ''Ad Konings' Book of Cichlids and all the other Fishes of Lake Malawi.'' . However, during the rainy season months of January to March, the waters are more muddy due to muddy river inflows.

European colonisation

The Portuguese trader Candido José da Costa Cardoso was the first

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

an to visit the lake in 1846. David Livingstone reached the lake in 1859, and named it Lake Nyasa. He also referred to it by a pair of nicknames: Lake of Stars and Lake of Storms. The Lake of Stars nickname came after Livingstone observed lights from the lanterns of the fishermen in Malawi on their boats, that resemble, from a distance, stars in the sky. Later, after experiencing the unpredictable and extremely violent gales that sweep through the area, he also referred to it as the Lake of Storms. On 16 August 1914, Lake Malawi was the scene of a brief naval battle during

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

. The British

gunboat A gunboat is a naval watercraft designed for the express purpose of carrying one or more guns to bombard coastal targets, as opposed to those military craft designed for naval warfare, or for ferrying troops or supplies. History Pre-steam ...

, commanded by a Captain Rhoades, received orders from the British Empire's high command to "sink, burn, or destroy" the German Empire's only gunboat on the lake, the , commanded by Captain Berndt. Rhoades's crew found the ''Hermann von Wissmann'' in a bay near Sphinxhaven, in German East African territorial waters. ''Gwendolen'' disabled the German boat with a single

cannon A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder during th ...

shot from a range of about . This brief conflict was hailed by ''

The Times ''The Times'' is a British Newspaper#Daily, daily Newspaper#National, national newspaper based in London. It began in 1785 under the title ''The Daily Universal Register'', adopting its modern name on 1 January 1788. ''The Times'' and its si ...

'' in

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

as the British Empire's first naval victory of World War I.

Borders

Tanzania–Malawi dispute

The partition of the lake's surface area between Malawi and Tanzania is under dispute. Tanzania claims that the international border runs through the middle of the lake. On the other hand, Malawi claims the whole of the surface of this lake that is not in Mozambique, including the waters that are next to the shoreline of Tanzania. Malawi currently administers these waters. Both sides cite the Heligoland Treaty of 1890 between the United Kingdom and Germany concerning the border. The wrangle in this dispute occurred when the British colonial government, just after they had captured Tanganyika from Germany, placed all of the waters of the lake under a single jurisdiction, that of the territory of

Nyasaland Nyasaland () was a British protectorate in Africa that was established in 1907 when the former British Central Africa Protectorate changed its name. Between 1953 and 1963, Nyasaland was part of the Federation of Rhodesia and Nyasaland. After ...

, without a separate administration for the Tanganyikan portion of the surface. Later in colonial times, two jurisdictions were established. The dispute came to a head in 1967 when Tanzania officially protested to Malawi; however nothing was settled. Occasional flare-ups of conflict occurred during the 1990s and in the 21st century. In 2012, Malawi's oil exploration initiative brought the issue to the fore, with Tanzania demanding that exploration cease until the dispute was settled.

Malawi–Mozambique border

In 1954, an agreement was signed between the

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...

and the Portuguese making the middle of the lake their boundary with the exception of Chizumulu Island and Likoma Island, which were kept by the British and are now part of Malawi.

Transport

began service on the lake in 1901 as the SS ''Chauncy Maples'': a floating clinic and church for the Universities' Mission to Central Africa. She later served as a ferry and is currently being renovated into a mobile clinic at Monkey Bay. The renovation was expected to be complete during the first half of 2014, but was halted in 2017. entered service in 1935. The ferry entered service in 1951. In recent years she has often been out of service, but when operational she runs between Monkey Bay at the southern end of the lake to Karonga on the northern end, and occasionally to the Iringa Region of Tanzania. The ferry entered service in 1980. By 1982 she was carrying 100,000 passengers each year., but as of 2014 she was out of service. She normally serves the southern part of the lake but if ''Ilala'' was out of service she operated the route to Karonga. The Tanzanian ferry was built in 1988. Her operator was the Tanzania Railway Corporation Marine Division until 1997, when it became the

Marine Services Company Limited Marine Services Company Limited (MSCL) is a Tanzanian company that operates Ferry, ferries, cargo ships and Tanker (ship), tankers on three of the African Great Lakes, namely Lake Victoria, Lake Tanganyika and Lake Nyasa. It provides services to ...

. ''Songea'' plies weekly between Liuli and Nkhata Bay via Itungi and Mbamba Bay. The worst Lake disaster was the sinking of the in 1946, which resulted in 145 deaths.

Wildlife

Wildlife found in and around Lake Malawi or Nyasa includes

Nile crocodile The Nile crocodile (''Crocodylus niloticus'') is a large crocodilian native to freshwater habitats in Africa, where it is present in 26 countries. It is widely distributed in sub-Saharan Africa, occurring mostly in the eastern, southern, and ce ...

hippopotamus The hippopotamus (''Hippopotamus amphibius;'' ; : hippopotamuses), often shortened to hippo (: hippos), further qualified as the common hippopotamus, Nile hippopotamus and river hippopotamus, is a large semiaquatic mammal native to sub-Sahar ...

monkey Monkey is a common name that may refer to most mammals of the infraorder Simiiformes, also known as simians. Traditionally, all animals in the group now known as simians are counted as monkeys except the apes. Thus monkeys, in that sense, co ...

s, and a significant population of

African fish eagle The African fish eagle (''Icthyophaga vocifer'') or the African sea eagle is a large species of eagle found throughout sub-Saharan Africa wherever large bodies of open water with an abundant food supply occur. It is the national bird of Malawi, ...

s that feed off fish from the lake.

Fish

Fishing

Pesce ad essiccare sulla riva del lago malawi

Lake Malawi has for millennia provided a major food source to the residents of its shores since its waters are rich in fish. Among the most popular are the four species of chambo, consisting of any one of four species in the subgenus ''Nyasalapia'' ('' Oreochromis karongae'', '' O. lidole'', '' O. saka'' and '' O. squamipinnis''), as well as the closely related '' O. shiranus''.Turner, G.F.; and N.C. Mwanyama (July 1992
Distribution and Biology of Chambo (Oreochromis spp.) in Lakes Malawi and Malombe.

Food and Agriculture Organization The Food and Agriculture Organization of the United Nations; . (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition and food security. Its Latin motto, , translates ...

, Fisheries and Aquaculture Department, FI:DP/MLW/86/013, Field Document 21. Retrieved 13 April 2017. Other species that support important fisheries include the

Lake Malawi sardine The Lake Malawi sardine, lake sardine, or usipa (''Engraulicypris sardella''), is an African species of freshwater fish in the family Danionidae. It is endemic to Lake Malawi and its outlet, the (upper) Shire River; it is found in Malawi, Mozamb ...

(''Engraulicypris sardella'') and the large kampango catfish (''Bagrus meridionalis''). Most fishing provides food for the increasing human population near the lake, but some are exported from Malawi. The wild population of fish is increasingly threatened by

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing Fish stocks, fish stock), resu ...

and

water pollution Water pollution (or aquatic pollution) is the contamination of Body of water, water bodies, with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and ...

. A drop in the lake's water level represents another threat, and is believed to be driven by water extraction by the increasing human population,

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

and

deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...

. The chambo and kampango have been particularly overfished (the kampango declined by about 90% from 2006 to 2016, ''O. karongae'' and ''O. squamipinnis'' by about 94%, and ''O. lidole'' might already be extinct) and they are now seriously threatened. The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

recognises 117 species of Malawi cichlids as threatened; some of these have tiny ranges and may be restricted to rocky coastlines only a few hundred metres long.

Cichlids

Lake Malawi is noted for being the site of

evolutionary radiation An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation, that may or may not be associated with an increase in morphological disparity. A significantly large and diverse radiation within ...

s among several groups of animals, most notably

fish. There are at least 700 cichlid species in Lake Malawi, with some estimating that the actual figure is as high as 1,000 species. The actual number is labelled with some uncertainty because of the many

undescribed species In taxonomy, an undescribed taxon is a taxon (for example, a species) that has been discovered, but not yet formally described and named. The various Nomenclature Codes specify the requirements for a new taxon to be validly described and named. U ...

and the extreme variation among some species, making the task of delimiting them very complex. Except for four species ('' Astatotilapia calliptera'', '' Coptodon rendalli'', ''Oreochromis shiranus'' and '' Serranochromis robustus''), all cichlids in the lake are

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the Malawi system, which also includes nearby smaller Lake Malombe and the upper Shire River.Oliver, M.K. (12 April 2015)
The Tilapias of Lake Malawi.
MalawiCichlids. Retrieved 13 April 2017. Many of these have become popular among

aquarium An aquarium (: aquariums or aquaria) is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. fishkeeping, Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aquati ...

owners due to their bright colors. Recreating a Lake Malawi biotope to host cichlids became quite popular in the aquarium hobby. Most Malawi cichlids are found in relatively shallow coastal waters, but '' Diplotaxodon'' has been recorded down to depths of and several (especially ''Diplotaxodon'', '' Rhamphochromis'' and '' Copadichromis quadrimaculatus'') are known from

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

waters. The cichlids of the lake are divided into two groups and the vast majority of the species are haplochromines. The sister species to the Malawi haplochromines is ''Astatotilapia'' sp. Ruaha (a currently undescribed species from Great Ruaha River), and these two separated between 2.13 and 6.76 million years ago (mya).Genner; Ngatunga; Mzighani; Smith; and Turner (2015). Geographical ancestry of Lake Malawi’s cichlid fish diversity. Biol. Lett. 11: 2015023. The earliest divergence within the Malawi haplochromines occurred between 1.20 and 4.06 mya, but most radiations in this group are far younger; in extreme cases species may have diverged only a few hundred years ago. The Malawi haplochromines are mouthbrooders, but otherwise vary extensively in general behaviour and ecology. Within the Malawi haplochromines there are two main groups, the haps and the

mbuna Mbuna (pronounced Mmm-boo-nah ) is the common name for a large group of African cichlids from Lake Malawi, and are members of the haplochromine tribe within the family Cichlidae. The name ''mbuna'' means "rockfish" in the language of the Tonga pe ...

. The haps (they were formerly included in ''

Haplochromis ''Haplochromis'' is a ray-finned fish genus in the family Cichlidae. It has been used as the default " wastebin taxon" for Pseudocrenilabrinae cichlids of the East African Rift, and as such became the "largest" fish "genus". Many of these cichl ...

'') can be further subdivided into three subgroups: The relatively large, often more than long, and aggressive

piscivore A piscivore () is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution (via water-bound amphibians during the Devonian period); insectivory came next; then in time, the more terrestrially adapted repti ...

s that roam various habitats in pursuit of prey, the open-water (although often not far from sand or rocks) utaka that feed in

schools A school is the educational institution (and, in the case of in-person learning, the building) designed to provide learning environments for the teaching of students, usually under the direction of teachers. Most countries have systems of ...

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

and typically are of medium size, and finally a subgroup of "aberrant" species that essentially are defined by them not fitting clearly into the other subgroups.Elieson, M
Haps Vs. Mbuna.
Retrieved 11 April 2017.Aquaticcommunity (2004–08
Haplochromis.
Retrieved 13 April 2017. Adult male haps generally display bright colors, while juveniles of both sexes and adult females typically show a silvery or grey coloration with sometimes irregular black bars or other markings. The second main haplochromine group are the mbuna, a name used both locally and popularly, which means "rockfish" in

Tonga Tonga, officially the Kingdom of Tonga, is an island country in Polynesia, part of Oceania. The country has 171 islands, of which 45 are inhabited. Its total surface area is about , scattered over in the southern Pacific Ocean. accordin ...

. They are found at rocky outcrops, territorially aggressive (although commonly found in high densities) and often specialised aufwuchs feeders. The mbuna species tend to be relatively small, mostly less than long, and often both sexes are brightly colored with males having egg-shaped yellow spots on their

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

(a feature particularly prevalent in the mbuna, but not exclusive to this group). The second group, the tilapia, comprises only six species in two genera in Lake Malawi: The redbreast tilapia (''Coptodon rendalli''), a widespread African species, is the only substrate-spawning cichlid in the lake. This large cichlid mainly feeds on macrophytes. The remaining are five mouthbrooding species of '' Oreochromis''; four chambo in the subgenus ''Nyasalapia'' (''O. karongae'', ''O. lidole'', ''O. saka'' and ''O. squamipinnis'') that are endemic to the Lake Malawi system, as well as the closely related ''O. shiranus'', which also is found in Lake Chilwa. The Malawi ''Oreochromis'' mainly feed on

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

, reach lengths up to depending on the exact species, and are mostly black or silvery-gray with relatively indistinct dark bars. Male chambo have unique genital tassels when breeding, which aid in egg fertilisation in a manner comparable to the egg-spots on the anal fin of haplochromines.

Non-cichlids

The vast majority of the fish species in the lake are cichlids. Among the non-cichlid native fish are several species of

cyprinids Cyprinidae is a family of freshwater fish commonly called the carp or minnow family, including the carps, the true minnows, and their relatives the barbs and barbels, among others. Cyprinidae is the largest and most diverse fish family, and t ...

(in genera '' Barbus'', '' Labeo'' and '' Opsaridium'', and the Lake Malawi sardine ''Engraulicypris sardella''), airbreathing catfish ('' Bathyclarias'' and '' Clarias'', and the kampango ''Bagrus meridionalis''), mochokid catfish ('' Chiloglanis'' and Malawi squeaker ''Synodontis njassae''), '' Mastacembelus'' spiny eel, mormyrids ('' Marcusenius'', '' Mormyrops'' and '' Petrocephalus''), the African tetra '' Brycinus imberi'', the poeciliid '' Aplocheilichthys johnstoni'', the spotted killifish (''Nothobranchius orthonotus''), and the mottled eel (''Anguilla nebulosa''). At a genus level, most of these are widespread in Africa, but ''Bathyclarias'' is entirely restricted to the lake.

Invertebrates

Molluscs

Lake Malawi is home to 28 species of

freshwater snail Freshwater snails are gastropod mollusks that live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs t ...

s (including 16 endemics) and 9

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

s (2 endemics, '' Aspatharia subreniformis'' and the unionid '' Nyassunio nyassaensis''). The endemic freshwater snails are all members of the genera '' Bellamya'', '' Bulinus'', '' Gabbiella'', ''

Lanistes ''Lanistes'' is a genus of freshwater snails which have a gill and an operculum (gastropod), operculum, aquatic animal, aquatic gastropod mollusks in the family Ampullariidae, the apple snails.Bouchet, P.; Neubauer, Thomas A. (2015). Lanistes Mo ...

'' and '' Melanoides''. Lake Malawi is home to a total of four snail species in the genus ''Bulinus'', which is a known intermediate host of

bilharzia Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever is a neglected tropical disease caused by parasitic flatworms called schistosomes. It affects both humans and animals. It affects the urinary tract or the intestines ...

. A survey in Monkey Bay in 1964 found two endemic species of snails of the genus ('' B. nyassanus'' and '' B. succinoides'') in the lake, and two non-endemic species ('' B. globosus'' and '' B. forskalli'') in lagoons separated from it. The latter species are known intermediate hosts of bilharzia, and larvae of the parasite were detected in water containing these, but in experiments C. Wright of the British Museum of Natural History was unable to infect the two species endemic to the lake with the parasites. The field workers, who spent many hours on and in the lake, did not find either ''B. globosus'' or ''B. forskalli'' in the lake itself. More recently, the disease has become a problem in the lake itself as the endemic ''B. nyassanus'' has become an intermediate host. This change, first noticed in the mid-1980s, is possibly related to a decline in snail-eating cichlids (for example, '' Trematocranus placodon'') due to overfishing and/or a new strain of the bilharzia parasite.

Crustaceans

Unlike Lake Tanganyika with its many endemic

freshwater crab Around 1,300 species of freshwater crabs are distributed throughout the tropics and subtropics, divided among eight family (biology), families. They show direct development and maternal care of a small number of offspring, in contrast to marine c ...

s and shrimp, there are few such species in Lake Malawi. The Malawi blue crab, '' Potamonautes lirrangensis'' ( syn. ''P. orbitospinus''), is the only crab in the lake and it is not endemic.Cumberlidge, N., and Meyer, K. S. (2011).
A revision of the freshwater crabs of Lake Kivu, East Africa.
' Journal Articles. Paper 30.Dobson, M. (2004).
Freshwater Crabs of Africa.
'' Freshwater Forum 21: 3–26. The atyid shrimp '' Caridina malawensis'' is endemic to the lake, but it is poorly known and has historically been confused with '' C. nilotica'', which is not found in the lake. Pelagic

ic species include two cladocerans ('' Diaphanosoma excisum'' and '' Bosmina longirostris''), three

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

s ('' Tropodiaptomus cunningtoni'', '' Thermocyclops neglectus'' and '' Mesocyclops aequatorialis''),Darwall; Allison; Turner; and Irvine (2010). Lake of flies, or lake of fish? A trophic model of Lake Malawi. Ecological Modelling 221: 713–727. and several

ostracod Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...

s (including both described and

Lake flies

Lake Malawi is famous for the huge swarms of tiny, harmless lake flies, '' Chaoborus edulis''.Morris, B. (2004). Insects and Human Life, pp. 73–76. These swarms, typically appearing far out over water, can be mistaken for plumes of smoke and were also noticed by David Livingstone when he visited the lake.van Huis, A.; H. van Gurp; and M. Dicke (2012). The Insect Cookbook: Food for a Sustainable Planet, p. 31. Malawi Tourism:
Interesting seasonal highlights of Malawi.
Retrieved 8 April 2017. The aquatic larvae feed on zooplankton, spending the day at the bottom and the night in the upper water levels. When they pupate they float to the surface and transform into adult flies. The adults are very short-lived and the swarms, which can be several hundred metres tall and often have a spiraling shape, are part of their mating behaviour.Andrew, D. (30 June 2015)
What Are These Strange Looking "Clouds"?
IFLScience. Retrieved 8 April 2017. They lay their eggs at the water's surface and the adults die. The larvae are an important food source for fish, and the adult flies are important both to birds and local people, who collect them to make '' kungu'' cakes/burgers, a local delicacy with a very high

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

content.

2015 mine leak

In January 2015, a sediment control tank collapsed at the Paladin Energy-owned uranium mine in Northern Malawi after a high intensity rain storm hit the area. It was revealed that approximately 50 litres of non radioactive material leaked into a local creek. Despite reports in local media of

radioactive contamination Radioactive contamination, also called radiological pollution, is the deposition of, or presence of Radioactive decay, radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is uni ...

the government conducted independent scientific tests on the local river system and found that there was no effect on the environment.

Swimming

The 25 km solo swim across Lake Malawi between Cape Ngomba and Senga Bay has been accomplished on 5 occasions by 16 swimmers 1992: Lewis Pugh 9hrs 52 minutes (UK/South Africa) and Otto Thanning (South Africa) 10hrs 5 minutes 2010: Abigail Brown (UK) 9hrs 45 minutes 2013: Milko van Gool (Netherlands) 8hrs 46 minutes and Kaitlin Harthoorn (US) 9hrs 17 minutes 2016: (current record) Jean Craven (South Africa), Robert Dunford (Kenya), Michiel Le Roux (South Africa), Samantha Whelpton (South Africa), Greig Bannatyne (South Africa), Haydn Von Maltitz (South Africa), Douglas Livingstone-Blevins (South Africa) 7hrs 53 mins 2019: Chris Stapley (

Eswatini Eswatini, formally the Kingdom of Eswatini, also known by its former official names Swaziland and the Kingdom of Swaziland, is a landlocked country in Southern Africa. It is bordered by South Africa on all sides except the northeast, where i ...

) and Jay Azran (South Africa) 8hrs 40 minutes, Andrew Stevens (

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

) 10hrs 50 minutes, and Ruth Azran (South Africa) 11hrs 8 minutes. That same year, Martin Hobbs (South Africa), became the first person to swim the full length of Lake Malawi (54 days), as well as setting the world record for longest solo swim in a lake