Lake Victoria, the largest lake in Africa by surface area, is home to an astonishing diversity of fish: In the middle of the 20th century, there were over 500 species in the lake, many of them endemic. The majority of these species belong to the tribe Haplochromini in the cichlid family. Haplochromine cichlids are small, often brightly colored, and well adapted to a wide range of habitats and ecological niches. Until the late 20th century, they constituted 80% of the total fish biomass in Lake Victoria and played a key role in nutrient cycles.
Historically, haplochromines were an important source of protein and other nutrients for many communities living on the shores of the lake. The various haplochromine species are collectively referred to as fulu in the Luo language; furu in Swahili; and nkejje in Luganda. Traditionally, the fish were caught in specially designed baskets. Today nets are more common. Once caught, and in order to improve their shelf life and flavor, the fish are sun dried and then smoked. They may be dried on the ground or on wooden skewers. The latter method makes it easier to smoke or roast the fish, or carry them to market. Because they are so small, haplochromines are eaten whole, often in a soup served with ugali (cornmeal), or cooked over charcoal.
Until recently, these fish were common in markets as far away as Nairobi, but today they are rarely caught for food: Instead, they are used as bait for Nile perch (Lates niloticus). British colonial authorities introduced Nile perch into Lake Victoria in the 1950s to boost the commercial fishing industry. The perch quickly consumed most of the haplochromines, driving an estimated 200 species to extinction. Haplochromines now constitute only about 1% of the fish biomass of the lake. Since the 1990s, the Nile perch population in Lake Victoria has declined due to overfishing. The haplochromine cichlids, in large part due to their ability to adapt rapidly to changing conditions, have begun to make a comeback—indeed, several species that were feared extinct have been rediscovered. However, the lake is still severely ecologically degraded: Pollution from industries and population centers, which grew up around the lake in response to the booming fishing industry, causes eutrophication (excessive buildup of nutrients). Apart from causing oxygen depletion, eutrophication reduces water clarity, which makes it difficult for haplochromines to correctly identify mates.
Establishing sustainable fishing practices and restoring the quality of the ecosystem is crucial, not only for preserving haplochromine diversity, but for the 30 million people who live in the Lake Victoria basin and rely on its resources.