Lates niloticus (Nile perch) is widespread throughout the Ethiopian Region of Africa, occurring commonly in all major river basins including Nile, Chad, Niger, Senegal and Volta. The nilotic population penetrates northwards well into the geographical limits of the Mediterranean Region and is present in the waters of Lake Mariout situated in the Nile Delta. Southwards the distribution includes parts of the Congo Basin. The most common place to find the Nile perch is in Lake Victoria where the species was introduced in 1962. (Hopson, 1972)
Nile perch are found in many different types of fresh water. They prefer warm, tropical waters (27°N – 7°S) where they grow to large sizes and occur in high densities. Adult Nile perch occupy all habitats in lakes and rivers (10-60 m in depth) where there is enough oxygen with the exception of rocks, swamps, and the pelagic zone. Small juveniles are restricted to shallow near-shore environments (Luna, 2002; Queensland Government, 2002). (FishBase, 2004; Queensland Department of Primary Industries and Fisheries, 2004)
Nile perch are silver in color with a blue tinge. They have a distinctive dark black eye with a bright yellow outer ring. Nile perch are usually seen around 2-4 kg, but have been caught and seen at sizes up to 200 kg (the largest at 232 kg). They average around 85-100 cm but can grow to 193 cm. The females are generally larger than males. The preopercle and pre-orbital bones are armed with spines, with a large spine on the free edge of the operculum. (FishBase, 2004; Queensland Department of Primary Industries and Fisheries, 2004)
The growth of the Nile perch is very fast during the first year. The rate then decreases during the second, third, fourth and fifth years. (Acere, 1984)
Nile perch are sexually dimorphic. The male has only anal and urogential openings just anterior to the anal fin, whereas the female has a genital orifice separate from the urinary opening. They become sexually mature at the age of 3 years. Males dominate the sex ratio up to 80 cm TL, while the females are dominate at 80 cm TL and above (Asila and Ogari, 1988). Ovulation takes place in the spring with the rising water temperature. Spawning is usually done in sheltered areas, but can also occur in open waters. (Hopson, 1972)
Nile perch live up to the age of 16 years. There is a higher mortality rate for males than females. (Hopson, 1972)
The diet of Nile perch consists of fishes, insects, crustacea and mollusks. The type of prey ingested by the predator depends on the predator size, prey availability and abundance within a given habitat (Ogari, 1984). Juvenile Nile perch feed on copepods, prawns in the genus Caridina, fish fry, small gastropods, and bivalves. As the fish matures and moves to greater depths haplochromine cichlids constitute over 95% of their food consumption. Occasional items found in the Nile perch's diet include smaller fish in the genera Barbus, Clarias, Haplochromis, Lates, Oreichromis, and Xenoclarias. Besides crustacean zooplankton, invertebrate prey includes snails, clams, and insects (odonate larvae, aquatic Hemiptera, mayflies in the genus Povilla, and larvae of phantom midges (Chaoborus). Fish in the genus Rastrineobola are very common in the diet in terms of occurrence, and are second to haplochromines (Acere, 1985). As Nile perch grow larger, they take larger prey. Nile perch less than 80 cm tend to feed on smaller fishes than those greater than 80 cm. This demonstrates that the predator is capable of shifting to other sizes of prey when more suitable sizes become scarce (Ogutu-Ohwayo, 1984). (Acere, 1984; Ogari, 1984; Ogutu-Ohwayo, 1984)
The Nile perch acts as a major predator in its native and introduced habitats.
Nile perch have been observed with several different kinds of parasites, Lernea (region after the operculum), arguilids (in the gills), and various nematodes (throughout the body). (Acere, 1984)
The Nile perch has yielded an increase in total fishery, and fishery-related employment has increased dramatically. Since the increase of Nile perch, larger factory fishing companies have thrived greatly. (Kitchel and Schindler, 1997)
The introduction of the Nile Perch to Lake Victoria has caused serious ecological problems. The richness and diversity of endemic cichlid species is rapidly declining. Over 300 native species have already been driven to extinction due to the feeding patterns of the Nile perch (Schofield, 1999). Although for the time being the strong increase of L. niloticus seems to be a favorable development for the fishing industry, the final consequences may be very serious for future fish production in the lake (Goudswaard and Witte, 1984). Since the increase of Nile perch, the accelerated decline in diversity has altered the food web structure and caused ecological changes due largely to human actions, which have profound socioeconomic effects (Kitchell and Schindler, 1997). The continuing degradation of Lake Victoria's ecological functions has serious long-term consequences for the ecosystem services it provides and may threaten social welfare in the different countries bordering its shores (Verschuren and Johnson, 2002). Also since the increase of Nile perch, smaller scale fishing companies have been hurt significantly. (Goudswaard and Witte, 1984; Kitchel and Schindler, 1997; Schofield, 1999; Verschuren and Johnson, 2002)
William Fink (editor), University of Michigan-Ann Arbor.
David Lipton (author), University of Michigan-Ann Arbor.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
marshes are wetland areas often dominated by grasses and reeds.
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an animal that mainly eats fish
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
Acere, T. 1984. Observations on the biology, age, growth, maturity and sexuality of Nile perch, *Lates niloticus* (Linne), and the growth of its fishery in the northern waters of Lake Victoria. FAO Fisheries Report, 335: 42-61.
Asila, A., J. Ogari. 1988. Growth Parameters and Mortality Rates of Nile Perch (*Lates niloticus*) Estimates from Length-Frequency Data in the Nyanza Gulf (Lake Victoria). FAO Fisheries Report, 389: 272-287.
FishBase, 2004. "Lates niloticus, Nile perch" (On-line). FishBase. Accessed 06/08/04 at http://www.fishbase.org/Summary/SpeciesSummary.cfm?genusname=Lates&speciesname=niloticus.
Goudswaard, P., F. Witte. 1984. Observation on Nile perch, *Lates niloticus* (L.), 1758, in the Tanzanian waters of Lake Victoria. FAO Fisheries Report, 335: 62-67.
Hopson, A. 1972. A Study of the Nile Perch (*Lates niloticus* (L.) Pisces: Centropomidae) in Lake Chad. Foreign and commonwealth office overseas development administration (Overseas Research Publication), 19: 1-90.
Kitchel, J., D. Schindler. 1997. The Nile perch in Lake Victoria: Interactions between predation and fisheries. Ecological Applications, 7 (2): 653-664.
Ogari, J. 1984. Distribution, Food and Feeding Habits of *Lates niloticus* in Nyanza Gulf of Lake Victoria (Kenya). FAO Fisheries Report, 335: 68-80.
Ogutu-Ohwayo, R. 1984. The Effects of Predation by Nile Perch, *Lates niloticus* (Linne) Introduced into Lake Kyoga (Uganda) in Relation to the Fisheries of Lake Kyoga and Lake Victoria. FAO Fisheries Report, 335: 18-41.
Queensland Department of Primary Industries and Fisheries, 2004. "Fish - Note, Nile Perch (Lates niloticus)" (On-line). Accessed November 1, 2002 at http://www.dpi.qld.gov.au/fishweb/2374.html.
Schofield, P. 1999. Interactions between Nile perch, *Lates niloticus*, and other fishes in Lake Nabugabo, Uganda. Environmental Biology of Fishes, 55 (4): 343-358.
Verschuren, D., T. Johnson. 2002. History and timing of human impact on Lake Victoria, East Africa. Proceedings of the Royal Society Biological Sciences Series B, 269 (1488): 289-294.