The cichlid fishes of Lake Kivu and Tanganyika

A queryable website on taxon and specimen information

• Introduction
• Literature cited

Introduction

The cichlids of the East African lakes

Cichlids are extraordinary fishes. Based on current estimates (Snoeks, 2000; 2001), the total species number within this family might well be around 2,400 species, which would make it the largest family of fishes, and maybe even of vertebrates.

Haplochromis rubescens Snoeks, 1994
Copyright © Royal Museum of Central Africa, Tervuren, Belgium

Although cichlids do occur in other tropical areas, and even in large numbers in the river systems of South and Central America, it is in the East African Lakes that cichlids have speciated in greatest profusion. In fact, the cichlids of these lakes constitute more than 10 % of the extant freshwater fishes of the world and each of the three larger lakes (Victoria, Tanganyika, Malawi) harbours more fish species than any other lake in the world. Species numbers for these lakes are estimated at 300 for Lake Tanganyika, 600 for Lake Victoria and 800 for Lake Malawi (Snoeks, 2001). Also the smaller lakes in the area, such as lakes Edward-George, Kivu, Kioga and others, hold relatively large numbers of cichlid fishes (lakes Albert and Turkana being an exception). Next to their speciose nature, another important feature of the East-Africa cichlids is their exceptional high degree of endemism. In each of the lakes, over 90 % of the cichlid species occurring, can only be found in one lake system and nowhere else. In addition, many taxa exhibit a substantial degree of intra-lacustrine endemism, their distribution being limited to parts of a lake only. These features alone make the Great African Lakes the largest centres of biodiversity in the vertebrate world.

These cichlid faunas provide many fascinating research topics. This has to do with their explosive speciation and adaptive radiation, making them prime subjects for systematic and evolutionary research. Equally fascinating are their fascinating behaviour, especially while reproducing, and their morphological and ecological specialisations. The main value of the cichlids of the Great African Lakes, however, is their economic importance as a readily accessible source of protein for the riparian people. In addition, these fishes are important to the specialised aquarium trade as one of the more exciting fish groups to be kept and bred by many hobbyists all over the world.

Cichlids of Lake Kivu and Lake Tanganyika

The scope of the present website is limited to information pertaining to the cichlid fish faunas of two lakes in the Albertine Rift region: lakes Kivu and Tanganyika. Lake Kivu harbours a 15 endemic haplochromines, the native Oreochromis niloticus and the introduced Oreochromis macrochir and Tilapia rendalli (Snoeks, 1994). The cichlid fauna of Lake Tanganyika is the most ancient and diverse of all African lakes. It is the only East African lake with a large component of substrate brooding cichlids next to the mouthbrooders. Its cichlid fauna occupies a wide array of ecological niches, from the biggest predator cichlid to small semi-pelagic sardine-like species, from specialised algae browsers to skilled scale scraping predators, from mollusc crushers to sexually dimorphic species, the female of which inhabits a snale shell in which it layes and guardes its eggs. The lake is also unique in having also several small non-cichlid species flocks.

Both lakes Tanganyika and Kivu were recently shown to have played an important role as evolutionary reservoirs for haplochromine cichlids in Central and East Africa. One phylogeographic study (Salzburger et al. 2005) demonstrated that Lake Tanganyika is the geographic and genetic cradle of all haplochromine lineages. In the ancestors of the replicate adaptive radiations of the 'modern haplochromines', behavioral (maternal mouthbrooding), morphological (egg-spots) and sexually selected (color polymorphism) key-innovations arose. It was suggested that these might be — together with the ecological opportunity that the habitat diversity of the large lakes provides — responsible for their evolutionary success and their propensity for explosive speciation. In a similar way it was discovered that Lake Kivu plays a pivotal role in the evolutionary history of the unique species-rich flock [more than 500 endemic haplochromine cichlid fishes] of lake Victoria. Surprizingly, it was found that the Lake Victoria cichlid flock is derived from the geologically older Lake Kivu and that the two seeding lineages may have already been lake-adapted when they colonized Lake Victoria (Verheyen et al. 2003).

The Albertine Rift
Copyright © Royal Museum of Central Africa, Tervuren, Belgium

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Literature cited

• Salzburger, W., Mack, T., Verheyen, E. & Meyer, A. 2005. Out of Tanganyika: Genesis, explosive speciation, key-innovations and phylogeography of the haplochromine cichlid fishes. BMC Evolutionary Biology 205, 5:17, http://www.biomedcentral.com/1471-2148/5/17.
• Snoeks J. (1994) The haplochromine fishes (Teleostei, Cichlidae) of Lake Kivu, East Africa : a taxonomic revision with notes on their ecology. Ann. Mus. Roy. Afr. Centr. Sc. Zool. 270 : 221 pp
• Snoeks J. (2000). How well known is the ichthyodiversity of the large East African lakes. In Rossiter, A. and Kawanabe, eds. Ancient lakes: Biodiversity, ecology and evolution. Advances in Ecological Research 31: 17-38. Academic Press.
• Snoeks J. (2001). Cichlid diversity, speciation and systematics: examples for the Great African Lakes. In: Coleman, R. (ed.). Cichlid research : state of the art. J. Aquaricult. Aq. Sci. 9, 150-166.
• Verheyen,E., Salzburger, W. Snoeks, J. & Meyer, A. (2003). Origin of the Superflock of Cichlid Fishes from Lake Victoria, East Africa. Science, 300: 325-329.

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