Taxonomic name: Oreochromis niloticus (Linnaeus, 1758)
Synonyms: Chromis guentheri (Steindachner, 1864), Oreochromis niloticus baringoensis (Trewavas, 1983), Oreochromis niloticus filoa (Trewavas, 1983), Oreochromis niloticus sugutae (Trewavas, 1983), Oreochromis niloticus tana (Seyoum & Kornfield, 1992), Perca nilotica (Linnaeus, 1758), Tilapia calciati (Gianferrari, 1924), Tilapia cancellata Nichols, 1923, Tilapia eduardiana (Boulenger, 1912), Tilapia inducta (Trewavas, 1933), Tilapia nilotica (Uyeno & Fujii, 1984), Tilapia regani (Poll, 1932), Tilapia vulcani (Trewavas 1933)
Common names: chhnoht (Khmer), chikadai (Japanese), munruvare (Swedish), Nile mouthbrooder (English), Nile tilapia (English), pla pla (Tagalog), planil (Thai), telepia (Japanese), tilapia (Tagalog), tilapie (German), trey tilapia (Khmer), wass
Organism type: fish Oreochromis niloticus (Nile tilapia) is a highly invasive fish that plagues a variety of ecosystems, particularly those located in the tropics. Oreochromis niloticus' effective mouthbrooding reproductive strategy allows it to increase in numbers at a rate which, not only crowds native species, but pollutes and unbalances the water column. Oreochromis niloticus is a frequently farmed aquatic species, due to its relative ease of culture and rapid reproduction rates. Most infestations are a result of aquaculture. Description
Compressed body; caudal peduncle depth equal to length. Cycloid scales. Lacks knobby feature on dorsal surface of snout. Sexual dimorphism not displayed in upper jaw length. First gill arch has 27 to 33 gillrakers. Interrupted lateral line (FAO, 2006; FAO, 2007). "Spinous and soft ray parts of dorsal fin continuous; dorsal fin with 16 - 17 spines and 11 to 15 soft rays. Anal fin with 3 spines and 10-11 rays. Caudal fin truncated. Colour in spawning season: pectoral, dorsal and caudal fins becoming reddish; caudal fin with numerous black bars" (FAO, 2006; FAO, 2007) Similar Species
Oreochromis aureus, Oreochromis mossambicus
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Occurs in:
coastland, estuarine habitats, lakes, marine habitats Habitat description
Nile tilapia (Oreochromis niloticus) is a tropical fish. It exists in a variety of freshwater and brackish habitats. Diurnal species. Its preferred temperature is 31-36 degrees Celsius but can survive from 12-42 degrees Celsius. O.niloticus prefers shallow water (FishBase, 2007). General impacts
Giani & Figurerdo (2005) write that "environmental problems may arise in aquatic environments after the introduction of Oreochromis niloticus" especially in areas with slow water renewal rates. Eutrophic water conditions frequently are a result of intensive O. niloticus production. O. niloticus' selective feeding regime can also unbalance algal constituents of the water column (Giani & Figurerdo, 2005). Although aquaculture helps meet population protein needs and can be a path to economic gain, biodiversity must be recognized as the basis for sustainable production (Ogutu-Ohwayo and Balirawa 2006). Because O. niloticus reproduce at such a rapid rate, they overcrowd and out-compete native species. This loss of biodiversity leads to genetic erosion and greater susceptibility to disease (Mahmud-ul-Ameen, 2000). Uses
Nile tilapia (Oreochromis niloticus) is a hugely important fish in aquaculture. The development of sex-reversal procedures in the mid-1970's allowed farmers to maintain high density all male populations, thus avoiding stunted and unmarketable fish that often resulted from crowded mixed-sex tanks.
The tilapia family (of which O. niloticus is a member) is the second most intensively farmed species in the world. China produces almost half of the worlds' tilapia crop, usually in the form of frozen whole fish (FAO, 2006; FAO, 2007). Tilapia is packaged in a variety of ways depending on the country of origin, including fresh or frozen fillets in "skin-on, skin-off, deep skinned, individually quick frozen, smoked, [or] sashimi..." forms (FAO, 2006; FAO, 2007). Notes
Genetically Improved Farmed Tilapia (GIFT tilapia) is a selective breeding project that aims to increase the effeciency of tilapia aquaculture efforts. Spearheaded by the International Centre for Living Aquatic Resources Management, the UN Development Program, and the Asian Development Bank, GIFT tilapia is derived from natural Oreochromis niloticus stock (Day & Gupta, 2000). GIFT tilapia is "exceptionally hardy and requires little or no expensive high protein feed to grow quickly" (ICLARM, 2007). ICLARM's website also notes that "the fish eats anything, from grass clippings to vegetable matter and suspended solids" (ICLARM, 2007). GIFT grows 60% faster and demonstrates a 50% higher survival rate compared to its base species, O.niloticus (ICLARM, 2007). Researchers express concern about biodiversity issues stemming from unintentional introductions. GIFT tilapias reproduce at an extremely high rate, can withstand crowded conditions and can thrive in a variety of brackish, fresh and saltwater conditions (Canonico et al. 2005). Geographical range
Native range: Africa: coastal rivers of Israel; Nile from below Albert Nile to the delta; Jebel Marra; Lake Chad basin and the rivers Niger, Benue, Volta, Gambia and Senegal (FishBase, 2007).
Known introduced range: Widely introduced for aquaculture, with many existing strains (FishBase, 2007). Introduction pathways to new locations
Aquaculture:
Live food trade:
Stocking:
Local dispersal methods
Aquaculture (local):
Escape from confinement:
Intentional release: Management information
The dramatic rise in Nile tilapia (Oreochromis niloticus) aquaculture in the last two decades is considered a concern from a management perspective. Low-cost tilapia aquaculture operations are closely linked to reductions in water quality, since small scale farmers generally opt for cage culture, a method that interfaces directly with open water systems. This method is closely linked to water pollution issues as well as declines in native fish and aquatic plant populations. In Central America, most attempts to bring about local prosperity by tilapia farming have failed. While tilapia fetches a good price in American markets, native markets in countries like Nicaragua generally offer a lower quality and a rather unappetising fish product. Furthermore, tilapia often does not have a place in native diets (GISD, 2006). Preventative measures: Mahmud-ul-Ameen (2000) writes that "tiliapia may be recommended for those areas where native species are scarce or absent...[but] in a country...rich in diversity, introductions should be very restricted." Chemical Faced with a tilapia threat, the island nation of Palau embarked on an eradication programme to remove tilapia from the country. A chemical (Rotenone) was applied directly to 5 infested sites. This effort was successful (Tilapia Eradication Project, 2004; Palau Biodiversity, undated). Cultural: The island nation of Palau used education campaigns to warn the population about the negative impacts of tilapia infestation to local flora and fauna (Tilapia Eradication Project, 2004). Nutrition
Nile tilapia (Oreochromis niloticus) is omnivorous. It feeds on phytoplankton, periphyton, aquatic plants, small invertebrates, benthic fauna, and detritus. O. niloticus can filter feed but it usually grazes the surface of periphyton mats (FAO, 2006; FAO, 2007). Reproduction
Sexual maturity begins at 5-6 months. Spawning begins at 24 degrees Celcius (FishBase, 2007). Nile tilapia (Oreochromis niloticus) establishes a territory and digs a nest and then the females deposit eggs in the nest. After fertilisation by the male, the female collects eggs in her mouth and leaves. The female incubates the eggs in her mouth until hatching, approximately 1-2 weeks later (FAO, 2006; FAO, 2007). "After fry are realeased, they may swim back into her mouth" if threatened (FAO, 2006; FAO, 2007). Because of mouthbrooding techniques, the number of eggs per spawn is smaller than other pond species, but survival rates of young are comparitively higher. Males can fertilise eggs from a succession of females, and if there is no drop in temperature females can spawn continuously (FAO, 2006; FAO, 2007). In large scale aquaculture settings, reproduction takes place in a series of tanks and incubation spaces. Between 21-28 days of age, fish are given a food containing a male hormone that changes the sex of female members. Male specimens of O. niloticus grow twice as fast, and maintainnig a mono-sex population avoids stunted growth of individuals due to overcrowding. Other farming techniques include pond culture, floating cage culture and recirculation tank methods (FAO, 2006; FAO, 2007). Lifecycle stages
Sexual maturity begins at 5-6 months. Nile tilapia (Oreochromis niloticus) can live up to 10 years and reach weights of 5kg (FAO, 2006; FAO, 2007). Reviewed by: Pam Fuller USGS/BRD, Nonindigenous Aquatic Species Program. Florida Integrated Science Center. USA
Compiled by: National Biological Information Infrastructure (NBII) & IUCN SSC Invasive Species Specialist Group (ISSG)
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Last Modified: Thursday, March 27, 2008
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