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   Tilapia zillii (fish)   
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    Taxonomic name: Tilapia zillii (Gervais, 1848)
    Synonyms: Acerina zilli (Gervais, 1848), Chromis andreae (Gunther, 1864), Chromis coeruleomaculatus (Rochebrune, 1880), Chromis faidherbii (Rochebrune, 1880), Chromis melanopleura (Dumeril, 1861), Chromis menzalensis (Mitchell, 1895), Chromis tristrami (Gunther, 1860), Chromis zillii (Gervais, 1848), Coptodon zillii (Gervais, 1848), Coptodus zillii (Gervais, 1848), Glyphisidon zillii (Gervais, 1848), Haligenes tristrami (Gunther, 1860), Sarotherodon zillei (Gervais, 1848), Sarotherodon zillii (Gervais, 1848), Tilapia faidherbi (Rochebrune, 1880), Tilapia melanopleura (Dumeril, 1861), Tilapia menzalensis (Mitchell, 1895), Tilapia multiradiata (Holly, 1928), Tilapia shariensis (Fowler, 1949), Tilapia sparrmani multiradiata (Holly, 1928), Tilapia tristrami (Gunther, 1860)
    Common names: akpadi sila (Ghana), akpasila (Ghana), amnun matzui (Hebrew-Israel), a-sannoh (Sierra Leone), bere (Chad), biare (Chad), biering (Chad), bugu (Nigeria), bulti (Arabic-Sudan), cichlid (English-Ghana), didee (Ghana), disiwulen (Burkina Faso), Engege (Uganda), Epia (Nigeria), Erihere (Uganda), falga (Nigeria), garagaza (Nigeria), gargaza (Nigeria), gba gba ferah (Sierra Leone), gbatchekede (Cote d'Ivoire), guring (Chad), ifunu (Nigeria), isiswe (Uganda), karfasa (Nigeria), karwa (Nigeria), ka-yainkain (Sierra Leone), kido (Kenya), kokine (Kenya), kpro ibre (Cote d'Ivoire), kuda (Sudan), loroto (Kenya), mango fish (English-Ghana), mojarra (Spanish-Mexico), mojarrita (Spanish-Mexico), mpupa (Nigeria), ngege, ngipie (Sierra Leone), ngorkei (Sierra Leone), njabb (Senegal), obrouyou (Cote d'Ivoire), pastenague boulee (French-Senegal), perege (Swahili-Tanzania), punavatsatilapia (Finland), redbelly tilapia (English), sato (Swahili-Tanzania), sili (Swahili-Kenya), silla (Ghana), sohn (Chad), striped tilapia (English-United States), tegr-pere (Burkina Faso), tha thompo (Sierra Leone), tihil (Chad), tilapia (Spanish-Mexico), tome (Nigeria), tsokungi (Nigeria), ukuobu (Nigeria), waas (Senegal), waas gnoul (Senegal), wesafun (Nigeria), Zilles Buntbarsch (German-Germany), zilli's cichlid (English-United States), zill's tilapia (English)
    Organism type: fish
    In its native, tropical range, Tilapia zillii is important as a food fish as well as for aquaculture. Tilapia zillii provided 70% of Egypt's fish production, however outside its native range, this freshwater fish has the ability to establish itself even in highly salinated waters, only being held back by a low tolerance to cold water. Often introduced for use in aquatic weed control, Tilapia zilli can alter native benthic communities through the elimination of macrophytes and exhibits aggressive behaviour towards other fish species.
    Tilapia zillii has a maximum length of 40cm (SL) and a maximum published weight of 300 grams with a total of 13 to 16 Dorsal spines. The non-breeding coloration of T. Zillii is dark olive on top and light olive to yellow-brown on the sides, often with an iridescent blue sheen. Lips are bright green and the chest is pinkish. Six to seven dark vertical bars cross two horizontal stripes on the body and caudal peduncle. Fins are olivaceous, covered in yellow spots with the dorsal and anal fins displaying an outline of a thin orange band. Caudal fin often grey with pale interstices with dots covering the entire fin. Adults display a black spot outlined in yellow. T. Zillii from 2 to 14cm (SL) have an entirely yellow to grey caudal fin with no dots, developing a greyish caudal fin with dots with increasing size. Spawning coloration is shiny dark green on top and sides, red and black on the throat and belly, and obvious vertical bands on the sides. Heads turn dark blue to black with blue-green spots. Eggs are green to olive green, sticky, 1-2 mm in diameter; relatively smaller than eggs of other cichlids (FishBase, 2008; Williams, 2008).
    Occurs in:
    estuarine habitats, lakes, marine habitats, water courses
    Habitat description
    Tilapia zillii generally prefer shallow, vegetated areas in a tropical climate but will live over sand, mud, or rock; tolerating a range of pH between six to nine. While temperatures between 20 to 32 degrees Celsius are optimal for T. zillii, it can tolerate temperatures between 11 to 36 degrees Celsius, becoming lethargic and vulnerable to predators and disease below 16 degrees Celsius. Mostly occurring in fresh water, T. zillii are often found in brackish waters and has occasionally been reported to be found in marine waters; tolerating salinity levels of up to 29-45 ppt (Costa-Pierce, 2003; FishBase, 2008; GSMFC, 2005).
    General impacts
    Adult Tilapia zillii are considered to be voracious herbivores, often decreasing plant density and changing the composition of native plants which can threaten many native aquatic organisms that depend on such plants for forage, protection, or spawning (GSMFC, 2005; Spataru, 1978).
    Tilapia zillii is used for aquaculture, commercial aquarium trade, a weed control agent, and as a recreational fishery for many countries through out the world (FishBase, 2008). In a study investigating the feeding preferences of T. zillii among four species of aquatic plants, it was determined that Chara sp. and Najas marina could be controlled by T. zillii in small lakes and ponds (Saeed, 1986).
    In many of the publications reviewed in creating this profile, a misspelling of the species name Tilapia zillii is used. It seems to be a common mistake to omit one of the i's at the end of the word zillii, often incorrectly being spelled T. zilli.
    Geographical range
    Native range: Benin, Cameroon, Central African Republic, Chad, The Democratic Republic of the Congo, Cote d’Ivoire, Egypt, Gambia, Ghana, Guinea, Guinea-Bissau, Israel, Jordan, Kenya, Lebanon, Liberia, Mali, Mauritania, Morocco, Niger, Nigeria, Senegal, Sierra Leone, Sudan, Togo, Tunisia, Uganda, West Sahara.
    Known introduced range: Antigua and Barbuda, Eritrea, Ethiopia, Russian Federation, Guam, United States, Islamic republic of Iran, Japan, Madagascar, Mauritius, Mexico, New Caledonia, Philippines, Sri Lanka, Syrian Arab Republic, Taiwan, United Republic of Tanzania, Turkey, United Kingdom, the Gulf of Suez (FishBase, 2008).
    Management information
    Preventative measures: The use of potentially invasive alien species for aquaculture and their accidental release/or escape can have negative impacts on native biodiversity and ecosystems. Hewitt et al, (2006) Alien Species in Aquaculture: Considerations for responsible use aims to first provide decision makers and managers with information on the existing international and regional regulations that address the use of alien species in aquaculture, either directly or indirectly; and three examples of national responses to this issue (Australia, New Zealand and Chile). The publication also provides recommendations for a ‘simple’ set of guidelines and principles for developing countries that can be applied at a regional or domestic level for the responsible management of Alien Species use in aquaculture development. These guidelines focus primarily on marine systems, however may equally be applied to freshwater.

    Copp et al, (2005) Risk identification and assessment of non-native freshwater fishes presents a conceptual risk assessment approach for freshwater fish species that addresses the first two elements (hazard identification, hazard assessment) of the UK environmental risk strategy. The paper presents a few worked examples of assessments on species to facilitate discussion. The electronic Decision-support tools- Invasive-species identification tool kits that includes a freshwater and marine fish invasives scoring kit are made available on the Cefas (Centre for Environment, Fisheries & Aquaculture Science) page for free download (subject to Crown Copyright (2007-2008)).

    Chemical: In 1975, the Florida Freshwater and Game Commission used Rotenone to eradicate Tilapia zillii from a small borrow pit, about 0.2 hectares in size (Taylor, 1986).

    Biological: The following species are known predators of Tilapia zillii: Micropterus salmoides in Kenya, Barbus canis in Israel, Gymnarchus niloticus (no location noted), and Lates niloticus as well as Mormyrops anguilloides in Nigeria (FishBase, 2008). T. zillii is not a mouth brooder and therefore can possibly be suppressed through competitive exclusion by mouth brooding species of fish (University of California Riverside, 2008).

    Tilapia zillii are omnivorous with juveniles being more carnivorous, consuming a number of different zoobenthos. Adults are especially herbivorous, consuming mainly aquatic plants. In a study of feeding habits of T. zillii within Lake Kinneret (Israel), the main source of food was Chironomida pupae (Diptera) in the spring and winter and zooplankton in the summer and autumn with algae supplementing the diet throughout the year (Spataru, 1978; Williams, 2008).
    Tilapia zillii are dioecious and begin courtship and mate selection in waters at or above 20 degrees Celsius. Both parents may help in nest building, constructing nesting depressions 20 to 25cm in width and 5 to 8cm in depth, often in bottoms with sand or pebbles and ample vegetation. Eggs are green, sticky, 1-2 mm in diameter, and have been found in waters ranging in temperature of 20 to 28 degrees Celsius. The adhesive eggs are laid directly on the substrate within the excavated nest. Males fertilize the eggs externally. Females have been reported to lay between 1,000 and 6,000 eggs at one time. Both parents fan water over the eggs with their fins and pick debris and dead eggs from the nesting depression. Nest complexity can be variable, often with simple nests and limited parenting at exposed sites and complex nests with brooding chambers in sheltered areas. T. Zillii is not a mouth brooder (FishBase, 2008; Williams, 2008; GSMFC, 2005).
    Lifecycle stages
    Spawning of Tilapia zillii takes 1 to 2 hours while hatching of the eggs takes between 48 and 74 hours. Fry form school which is protected by both parents. 1 month after spawning, T. zillii can spawn again. In its native range, Tilapia zillii can breed throughout the year. Maturity is reached at about age 2, growing to 170 mm in year 1 and 315 mm in year 2. Longevity of T. zillii is around 6 years (Williams, 2008; GSMFC, 2005).
    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)
    Last Modified: Tuesday, 22 April 2008

ISSG Landcare Research NBII IUCN University of Auckland