fishkeeping is the more popular area of the hobby. This is evident because most
pet stores contain some variety of freshwater fish. Most freshwater aquaria are
community tanks, meaning they contain many different species of fish. It is
also common to have a single species breeding aquarium. A more difficult but
equally popular type of aquarium is creating aquascapes using live aquatic
plants and fish. Freshwater aquarium fish can come from many different
locations around the world. The most common areas these species come from are
the Amazon River basin, parts of Asian countries, and throughout Africa. For
the purposes of this paper, a common type of freshwater aquarium fish are
cichlids. These fish come from Lake Victoria, Lake Malawi, and Lake Tanganyika
of eastern Africa, as well as the Amazon River basin. Generally, these various
species are easy to breed and care for. The only difficulty is with choosing
the appropriate community of fish because they can be aggressive.
freshwater aquarium trade is a very large market. Species come from all over
the world. One type of fish that is the most popular are cichlids. Cichlids are
one of the largest vertebrate families in the world. They are most diverse in
Africa and South America. Africa, by far, contains the largest amount, but the
actual number of species is unknown, with estimates varying between 2,000 and
3,000 (Carleton 2009). Cichlids species sizes range
from as small as 2.5 cm to about 1 m in length. Many cichlids play vital roles
in things other than the aquarium hobby. Tilapia, for example, are important
food fish. The most popular aquarium fish come from South American and are
called angelfish, oscars, and discus. Cichlids have the largest number of
endangered species among vertebrate families (Carleton 2009). Cichlids have evolved
rapidly into a large number of closely related and diverse species within the large
lakes of Tanganyika, Victoria, Malawi. Cichlids are found mostly at shallow
depths, with a few exceptions.
Victoria is one of Africa’s great lakes. Lake Victoria occupies a shallow
depression in Africa, so the average depth is only about 150 feet. The lake
contains hundreds of cichlid species. Lake Victoria used to be very rich in
fish, but many of these became extinct during the last 50 years (Wolfshaar et al.
The main group of cichlids in Lake Victoria are the haplochromine cichlids. The
lake contains more species than any other lake in the world other than Lake
Malawi. The haplochromines are also part of several smaller lakes nearby have
some sort of connection to Lake Victoria and are relatively shallow (Katunzi et al.
Lake Kyoga is a good example of a lake that was easily accessible to Victoria
cichlids. However, due to the introduction of invasive species in this lake and
Lake Victoria, haplochromines have become increasing hard to find.
During the 1950’s,
Nile perch were introduced into Lake Victoria. This species of fish can grow to
be about six feet long. The decision was made to introduce this fish in order
to increase the amount of fish that could be caught for consumption (Wolfshaar et al.
Before about 1995, Lake Victoria supported Africa’s largest inland fishery. Haplochromines
and other native species continued to dominate fisheries until the 1970’s (van Zwieten et
After this point, there was a strong shift towards the catch of non-native Nile
perch. At the peak of catching Nile perch in the early 1990’s, over 500,000
tons were caught annually. However, these numbers have declined significantly in
the years to follow because of possible overfishing.
As with most
invasive species, the expected results of introducing the Nile perch did not go
well for the haplochromines and ecology of the lake. As a result of predation
by the Nile perch, many changes to the lakes ecosystem happened. It is
estimated that at least about 40 percent of Lake Victoria haplochromines have
become extinct over the last 50 years or so (van Zwieten et
It was feared that this number was even higher, but several species that were
feared extinct have been rediscovered after the Nile perch started to decline
in the 1990’s.
Another impact the
Nile perch had on the overall ecology of the lake was an alteration in the food
chain. This decreased the number of algae eating fish found in the lake and
allowed for the algae to grow at an alarming rate (van Zwieten et
The increasing amounts of algae increased the amount of dead plant material
that falls to the deeper portions of the lake before decomposing. The process
of decomposition reduces the amount of oxygen in the area. Without oxygen, fish
cannot exist in the deeper parts of the lake. This essentially forced all life
to exist within a narrow range of depth. Haplochromines have been adapting to
the changing ecology of Lake Victoria. Some examples of adaptions include a
larger gill area for oxygen-poor water,
changes in the feeding apparatus, and changes to the eyes (Brawand et al.
Some of the threatened Lake Victoria cichlid species have populations located
in zoos, public aquaria, and among private aquarists. There are even a few
species that are extinct in the wild and only found in captivity. The steep
decline in the haplochromines of Lake Victoria has led to them becoming a
rarity in the aquarium hobby. Most haplochromine are hard to find aside from
one or two species that are thriving in the lake or have been bread in
abundance. The literature has not totally agreed upon a solid reason for the
demise of the haplochromine cichlids, although human involvement has proven to
be the overall factor (van Zwieten et
The next and most important step is to decide what to do about saving the
species we have and preserving the ecology of Lake Victoria.