The Great Lakes of East Africa
By Marc Elieson
This article has the purpose of introducing you to the three great lakes of east Africa: Lakes Victoria, Malawi, and
Tanganyika.
These three lakes are in eastern Africa, nestled in and around what is known as Africa’s Great Rift Valley. This valley
extends for more than 3,000 miles, beginning in Syria and traveling through southwestern Asia before it enters into
southeastern Africa. This valley is anywhere from 18 to 60 miles wide, and ranges in elevation from 1,300 feet below
sea level to 6,000 feet. This valley contains some of Africa’s most spectacular scenery, being flanked by volcanoes and
mountains, including Mt. Kilimanjaro, the highest peak in Africa, at 19,340 feet.
In eastern Africa the valley separates into two branches: the Eastern Rift and the Western Rift. The Eastern Rift, or
main section of the valley, cuts across Ethiopia and then south across Kenya, Tanzania, and Malawi to Mozambique.
Lake Malawi lies in the Eastern Rift branch. Just north of Lake Malawi is the western branch, which runs north along
the eastern border of Zaire.
Within this branch of the Great Rift Valley are Lake Tanganyika and several other smaller lakes, including Lakes Edward
and Albert. Lake Victoria does not lie in the Great Rift Valley but between its main and western branches.
LAKE VICTORIA:
Also known as Victoria Nyanza, Lake Victoria is bordered by Uganda, Kenya, and Tanzania. It has an area of 26,830
square miles (the size of Ireland), and is 250 miles long at its greatest width, making it the world’s second largest
freshwater lake, after Lake Superior. It also has an average depth of 120 feet, with its deepest point reaching 250 feet.
Lake Victoria receives its water from many rivers, the largest being the Kagera. The lake then drains into the Nile
through Owen Falls, where there is a man-made hydroelectric dam.
Lake Victoria was once home to more than 500 different species of Cichlids before Nile perch were introduced to the
lake by the lake’s residents. Introduced in the 1950s to provide food for the people of the lake and develop commercial
fishery, these predators grow up to 6 feet long, and have successfully wiped out some 250 of these 500 Cichlid species.
The diversity of species is incredible when you realize that all of western Europe hosts only around 60 species of
freshwater fish. Even more astonishing is that it's believed that all of these different species evolved from a single
progenitor.
The water in Lake Victoria is much less clear than that in Lakes Malawi and Tanganyika. Transparency has been
measured between less than 4 and 10 feet in inshore areas. The pH is alkaline, ranging from 7.2 to 8.6, and carbonate
hardness is between 2 and 8 dH. The temperature can be as low as 70 degrees at the surface during the dry season and
reaches 81 degrees during the wet season. Interestingly, it receives more rainfall (about 200 to 250 centimeters a year)
in the middle than anywhere near its edges. Some biotopes of the lake resemble those of Lake Malawi, with lots of
large rocks.
LAKE MALAWI:
Lake Malawi, known locally as Lake Nyasa, is the ninth largest lake in the world and lies between the countries of
Malawi on the west and Tanzania and Mozambique on the east. It is 360 miles long and 25 miles wide, with an
approximate area of 8,683 sq mi, and reaches depths of 2,300 feet. The lake has a visibility of up to 70 feet.
Lake Malawi contains a greater variety of indigenous species of Cichlid fishes than any other lake in the world. World
Wildlife Fund researchers have identified over 500 species to date that are not found anywhere else in the world. That
is more than all of the freshwater species found in all the waters of both Europe and North America. The Cichlids of
Lake Malawi, perhaps even more so than the Cichlids from the other two rift lakes, are brightly colored and patterned.
For this reason, they have been a big hit with aquarists all over the world.
Among these popular Cichlids are the Mbuna and the Haps.
The “Mbuna” (i.e., rock-dwelling fish) are a large group of Cichlids that live among large piles of rocks along the
shoreline. They are usually seen in large groups, but are by no means a schooling fish. In some areas of Lake Malawi, 20
fish per square meter is not uncommon. Both sexes of the more than 100 species of Mbuna are unusually colorful,
whereas typically, only males have color. They are very colorful with bright patterns of horizontal stripes or vertical
bars. Mbuna are smaller and tend to have flat faces, which enables them to better scrape algae from rocks.
Most Haps are piscivores (fish eater), unlike the vegetarian Mbuna. There are some exceptions to this generalization,
however, but these do well on a piscovore's diet nonetheless. Haps are aggressive, but not as aggressive as the
vegetarian Mbuna. They have long, slender, almost torpedo-like bodies, and cruise the open water. Most of these fish
are silver or gray when small, and the males become very brightly colored as they mature. Females typically remain
without color.
The water chemistry in Lake Malawi is very similar to that of Lake Victoria. For this reason, many species from these
two lakes can be housed together. Lake Malawi's pH ranges from 7.8 to 8.6, with a total hardness of 4.0-6.0 dH. The
reason for the variation is caused by the level of Carbon Dioxide dissolved in the water. In areas with turbulent water,
where the water is better aerated, the pH is higher, while in calm bays, the level of dissolved Carbon Dioxide is higher;
consequently, the pH is lower there. Surface temperature ranges from 76 to 85 degrees, while the temperature at
lower levels of the lake remain at a constant 70 degrees. Carbonate hardness ranges from 6.0 to 8.0.
LAKE TANGANYIKA:
Lake Tanganyika is the longest lake in the world, boasting a length of 420 miles, and is the second deepest in the world,
reaching a depth of 4,710 feet. It is the second largest lake in Africa, after Lake Victoria, covering about 12,700 square
miles. At its widest point it is 45 miles wide. It is bordered on the east by Tanzania, on the north by Burundi, on the
west by the Democratic Republic of the Congo (formerly Zaïre), and on the south by Zambia. Lake Tanganyika’s only
outlet is the Lukuga River, which flows into the Congo River.
As a result of having just one outlet, this rift lake has a particularly high mineral content. This is because most of the
salts that flow into it don't leave, but rather get left behind as the water evaporates.
The water chemistry of Lake Tanganyika, is much more alkaline and hard than is the water from Lakes Malawi and
Victoria. Its pH levels range from 8.6 to 9.5, with a total hardness of 11-17 dH, and carbonate hardness being between
16 and 19 dH. The water in the lake is very clear, with visibility up to 70 feet. In the upper 130 feet, the water is
oxygen-rich. This is an important point to consider when caring for Tanganyikans in captivity. Their water should be as
close to saturation as possible. Surface temperature ranges from 76 to 82 degrees, while the temperature at lower
levels of the lake remain at a constant 70 degrees. It is important to keep the temperature of the water within this
range, as water with a temperature higher than 84 degrees can be lethal to Tanganyikans. This is because as the
temperature increases, their metabolism speeds up, and their demand for oxygen increases with it. At 85 degrees the
oxygen content must be near saturation or they will die of suffocation.
The lake is known for its many varieties of fish, of which are almost 200 unique Cichlid species. Crocodiles and
hippopotamuses are often found on the shores of the lake. The biotope of the lake is sandy, and therefore, these fish
are best kept in an aquarium with sand, not gravel. This is especially true of the sand-dwelling species. Many of the
Tanganyikan species are small and can be housed in 10 and 20-gallon aquariums, such as the shell-dwelling genera
Neolamprologus and Lamprologus.
On a separate sheet of paper, describe a biotope aquarium that you would create resembling one of the African Great Lakes.
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In the first paragraph describe the lake that you chose. How large is it? How deep? How many fish species?
In the second paragraph describe what your aquarium would look like. Would you have rocks? Sandy bottom? Be sure to include
the special water conditions. You may include a picture to help you describe your aquarium.
In the third paragraph explain why African cichlids would not thrive in an Amazon biotope aquarium.