page_title: Lake Victoria
section_title: Cichlid fish
hierarchical_section_title: Lake Victoria / Native wildlife / Cichlid fish
caption_attribution_description: English: Pundamilia (Haplochromis) nyererei "Mwanza Gulf" (Witte-Maas &amp; Witte, 1985) subdominant male, photo taken in captivity. F1 stock derived from 'Old World Exotics' (aka Laif DeMason) who imported some wild caught Victorian cichlids in 2007. 'The exact location was unknown so they were given the somewhat generic location of Mwanza Gulf.'
context_page_description: Lake Victoria is one of the African Great Lakes.
  The lake was named after Queen Victoria by the explorer John Hanning Speke, in his reports—the first Briton to document it. Speke accomplished this in 1858, while on an expedition with Richard Francis Burton to locate the source of the Nile River. This expedition was financially sponsored by the Royal Geographic Society.
  With a surface area of approximately 59,947 square kilometres, Lake Victoria is Africa's largest lake by area, the world's largest tropical lake, and the world's second largest fresh water lake by surface area after Lake Superior in North America. In terms of volume, Lake Victoria is the world's ninth largest continental lake, containing about 2,424 cubic kilometres of water. Lake Victoria occupies a shallow depression in Africa. The lake has a maximum depth of between 80 and 84 metres and an average depth of 40 metres. Its catchment area covers 169,858 square kilometres. The lake has a shoreline of 7,142 kilometres when digitized at the 1:25,000 level, with islands constituting 3.7 percent of this length. The lake's area is divided among three countries: Kenya, Uganda, and Tanzania.
context_section_description: Lake Victoria formerly was very rich in fish, including many endemics, but a high percentage of these became extinct during the last 50 years. The main group in Lake Victoria is the haplochromine cichlids (Haplochromis sensu lato) with more than 500 species, almost all endemic, and including an estimated 300 that still are undescribed. This is far more species of fish than any other lake in the world, except Lake Malawi. These are the result of a rapid adaptive radiation in the last circa 15,000 years. Their extraordinary diversity and speed of evolution have been the subjects for many scientists studying the forces that drive the richness of life everywhere. The Victoria haplochromines are part of an older group of more than 700 closely related species, also including those of several smaller lakes in the region, notably Kyoga, Edward–George, Albert, and Kivu.
  Most of these lakes are relatively shallow (like Victoria) and part of the present-day upper Nile basin. The exception is Lake Kivu, which is part of the present-day Congo River basin, but is believed to have been connected to Lakes Edward and Victoria by rivers until the uplifting of parts of the East African Rift. This deep lake may have functioned as an "evolutionary reservoir" for this haplochromine group in periods where other shallower lakes in the region dried out, as happened to Lake Victoria about 15,000 years ago. In recent history only Lake Kyoga was easily accessible to Victoria cichlids, as further downstream movement by the Victoria Nile (to Lake Albert) is prevented by a series of waterfalls, notably Murchison. In contrast, the Owen Falls (now flooded by a dam) between Victoria and Kyoga were essentially a series of rapids that did not effectively block fish movements between the two lakes.
  The Victoria haplochromines are distinctly sexually dimorphic (males relatively brightly colored; females dull), and their ecology is extremely diverse, falling into at least 16 groups, including detritivores, zooplanktivores, insectivores, prawn-eaters, molluscivores and piscivores. As a result of predation by the introduced Nile perch, eutrophication and other changes to the ecosystem, it is estimated that at least 200 species (about 40 percent) of Lake Victoria haplochromines have become extinct, including more than 100 undescribed species. Initially it was feared that this number was even higher, by some estimates 65 percent of the total species, but several species that were feared extinct have been rediscovered after the Nile perch started to decline in the 1990s. Several of the remaining species are seriously threatened and additional extinctions are possible. Some species have survived in nearby small satellite lakes, have survived in refugias among rocks or papyrus sedges (protecting them from the Nile perch), or have adapted to the human-induced changes in the lake itself. Such adaptions include a larger gill area (adaption for oxygen-poor water), changes in the feeding apparatus, changes to the eyes (giving them a better sight in turbid water) and smaller head/larger caudal peduncle (allowing faster swimming). The piscivorous (affected by both predation and competition from Nile perch), molluscivorous and insectivorous haplochromines were particularly hard hit with many extinctions. Others have become extinct in their pure form, but survive as hybrids between close relatives (especially among the detritivores). The zooplanktivores have been least affected and in the late 1990s had reached densities similar to, or above, the densities before the drastic declines, although consisting of fewer species and often switching their diet towards macroinvertebrates. Some of the threatened Lake Victoria cichlid species have captive "insurance" populations in zoos, public aquaria and among private aquarists, and a few species are extinct in the wild (only survive in captivity).
  Before the mass extinction that has occurred among the lake's cichlids in the last 50 years, about 90 percent of the native fish species in the lake were haplochromines. Disregarding the ha
caption: Unlike many other Lake Victoria cichlids, Haplochromis nyererei remains common.[32] Compared to several other cichlids, its eyes are particularly sensitive to light, especially red, which is less affected by the decrease in water clarity caused by eutrophication than short wavelength colors[33]
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