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Home , Mozambique tilapia, Nile tilapia, Oreochromis, Spotted tilapia

Pest profiles mossambicus -

Overview p.1 Detailed Synonyms p.2 information Classification p.2 Appearance p.2 Taxonomic description p.2 Size p.2 Natural & introduced distrubition p.2 Diet p.3 Reproduction p.4 Ecological tolerances p.5 Ecological impacts p.6 Glossary p.8 References p.8 Contact details p. 12

Common names: crustaceans, molluscs and will opportunistically feed on fish eggs . Also known as Mozambique , and small fish. Kurper or mud bream (South ), Ikun mujair or Miracle fish (Indonesia). Reproduction: O. mossambicus is a polygynous, sexually dimorphic, maternal Appearance: mouthbrooder. Mature males aggregate at the start of the breeding There are two forms of Mozambique tilapia present in northern season in shallow margins of waterbodies and establish courtship Queensland: the "pure form" found in the Townsville-Thuringowa arenas (leks). Each male digs a shallow circular pit which is region and a form, found in the Cairns region, Atherton aggressively defended and used for display to attract a receptive Tablelands and the Burdekin system. Both forms are deep- female. After fertilisation of eggs within the pit, the female collects bodied with almost symmetrical, tapered extensions to the rear the eggs in her mouth and establishes a brooding territory edge of the single dorsal and anal fins. These fin extensions are elsewhere Reproduction is regulated by temperature with longer in males than in females. The jaws of sexually mature males spawning thresholds for the reported between 18° and of both forms are enlarged with the upper profile of the head often 25°C. Spawning is aseasonal in higher, subtropical latitudes (4-6 concave. months), about 9-10 months in the tropics and virtually continuous in equatorial regions where temperatures remain year-round above Size: at least 24°C. The typical size range (TL) reported for adult male O. mossambicus is 30 - 44cm from tropical/ subtropical regions where Brood size is related to female body size and can range between a conditions are within the species' normal tolerance ranges. Adult few hundred for stunted (early maturing) females to between 2000 females are smaller and, under similar conditions, range and 4000 for large females > 25cm SL. The species is a multiple approximately in size from 25-33 cm. spawner and can produce several broods during a season, the Under more extreme conditions at the limits of its range or in frequency strongly influenced by temperature - spawning intervals stressful environments (eg. shallow drying pools, marginal have been reported of between 30 and 40 days, resulting in about 5 ), the species can mature at a small size (stunting), and the broods in subtropical regions and about 8-10 broods in the tropics. maximum size range for males can be between 10-30cm TL. Because of the reproductive mode, survivorship of eggs and fry can be very high, with rates (at least under laboratory conditions) Natural and introduced distribution: reported of between 50 and 95%, thus allowing for very rapid It occurs in coastal regions eastern Africa between 33°S lat and population increase under favourable conditions. 17°S lat. Including Botswana, , Lesotho, Mozambique, Swaziland, and .It has been introduced Ecological tolerances: into at least 90 countries including Australia, where it occurs in Can survive high and low temperatures, high salinity, low oxygen two states: Western Australia and Queensland. and high and low pH.

Habitat: Ecological impacts: Inhabits slow flowing and streams and still water habitats The highly invasive O. mossambicus has been implicated in the such as and lagoons and in both fresh and brackish waters. A decline or disappearance of resident species from freshwater, population has even established on a marine atol in the central estuarine and marine habitats in several countries following its Pacific. A 'type' of the species is the lower River, introduction. It can have negative impacts on aquatic communities central Mozambique (eastern Africa, 18° 46'S) which is virtually on through grazing or predation, interference competition the same latitude as Ingham (18° 43'S). (overcrowding) for food and space, as a vector of disease-causing pathogens, or by activities which lead to changes in the abiotic Diet: environment (e.g., loss of water quality which may affect Mozambique tilapia consumes a wide range of food items, survivorship of resident species). although it is predominantly a benthic feeder on plant material including filamentous and unicellular , water weeds, terrestrial plants and organic . It will also consume cyanobacteria, aquatic invertebrates such as insect larvae, small >1< Detailed information

Synonyms Taxonomic description Chromis mossambicus (Peters 1852) O. mossambicus (pure form) Tilapia mossambica (Peters 1852) 1. Vertebrae 28-31, mode 30. Sarothredon mossambica (Peters 1852) 2. Fin formula: D XV-XVII 26-29, A III 9-12, (mode 10); Sarotherodon mossambica (Peters 1852) lower gill rakers 14-20 (mode 17,18) Sarotherodon mossambicum (Peters 1852) 3. Pharyngeal teeth very fine in 3-5 series the dentigerous Oreochromis mozambica (Peters 1852) area with narrow lobes, the blade in adults longer than Tilapia mossambica mossambica (Peters 1852) dentigerous area Tilapia mossambicus (Peters 1852) 4. Scales rows on the cheek. 30-32 in lateral line series Oreochromis mossambicus (Peters 1852) (mode 31). 3.5 to 4.5 between origin of and Oreochromis mossambica (Peters 1852) lateral line; 4-6 between pectoral and pelvic fins Chromis niloticus mossambicus (Peters 1852) 5. Caudal fin not densely scaled; truncate with rounded Cromis mossambicus (Peters 1852) corners Tilapia dumerili (Steindachner 1864) 6. Genital papilla of male simple or with a shallow distal Tilapia dumerilii (Steindachner 1864) notch Chromis dumerilii (Steindachner 1864) Chromis vorax (Pfeffer 1893) Size Tilapia vorax (Pfeffer 1893) Maximum total length (TL max) recorded for a number of Sarotherodon mossambicus natalensis (Weber 1897) populations of Mozambique tilapia Chromis natalensis (Weber 1897) Location TL Source Tilapia arnoldi (Gilchrist & Thompson 1917) max (cm) Classification Ross River weirs (1997/8), Townsville, 43.8 Webb, unpubl. data Order Perciformes Qld, Australia Suborder Labroidei Inyamiti pan, KwaZulu, South Africa 43.2 Bruton & Allanson Family Cichlidae 1974 Tribe Tilapiini Ross River weirs (1992) Townsville, Qld, 41.3 Webb, unpubl. data Oreochromis Australia Species mossambicus North Pine Dam, Brisbane, Qld, 41.2* Blühdorn et al. 1990 Australia Appearance Egyptian culture 38.0 Bruton & Allanson "Pure form" (adult): Female and non-breeding male silvery grey to 1974 pale olive with 2-5 mid lateral blotches and some of a more dorsal Curralea (1990), Townsville, Qld, 36.4 Milward & Webb series may be absent in adults. Breeding male typically dark olive to Australia 1990 black with white to yellow lower parts of head (on the operculum, Reservoir, Trinidad 35.6 Hickling 1961 cheek and throat) and red margins to dorsal and caudal fins. Depth of body 36-49.5% of Standard Length (SL). Kiribbanara Reservoir, Sri Lanka 35.5 De Silva 1985 Ross Dam, Townsville-Thuringowa, Qld, 34.5 Webb 2006 "Hybrid form" (adult): Adults tend Australia to have a narrower body with Pimburettewa Reservoir, Sri Lanka 33.0 De Silva 1985 longer extensions to the dorsal and Tingalpa Dam, Brisbane, Qld, Australia 32.6* Blühdorn et al.1990 anal fins than the pure form. Also, Mahagama Reservoir, Sri Lanka 32.0 De Silva 1985 paired fins typically are red with a Cairns, Qld, Australia 31.9* Blühdorn et al. 1990 much wider band of red on the Kaudulla Reservoir, Sri Lanka 28.0 De Silva 1985 caudal fin and a reddish orange tinge to the general body colour. Breeding males with similar dark- Guthries , Cairns, Qld, Australia 26.2* Blühdorn et al. 1990 olive to black colour and yellow on lower head and throat as the Lake Sibaya, KwaZulu, South Africa 26.0 Bruton & Allanson pure form. Depth of body usually <45% of SL. 1974 Yodawewa Reservoir, Sri Lanka 25.0 De Silva 1985 Fry and juveniles of both forms are similar in York Dam, Jamaica 22.0 Hickling 1961 appearance. They are pale olive to si lvery Gascoyne River, WA, Australia 15.4* Blühdorn et al. 199 grey. Fry to about 60mm to 80mm SL have Buffalo Springs, Kenya 10.0 Whitehead 1962 vertical bars with or without mid-lateral blotches, but no horizontal stripes. A clear * SL data converted to TL by formula given by Blühdorn et al. ringed (black) tilapia spot is present on the 1990 rear part of the dorsal fin. In fish approximately >80mm, the tilapia spot Natural & Introduced distribution appears as the intensified lower end of a grey oblique bar which The species is now one of the most widely distributed fish species eventually disappears in the adult. and has been introduced into at least 90 countries including Australia, where it occurs in two states: Western Australia and Queensland, and established in 80 of these (see fig 1). The species was introduced primarily for or to establish commercial or recreational fisheries (especially in impoundments), but was also introduced as a biocontrol agent (for larvae, and aquatic weeds), as a

>2< Distribution & Diet

World distribution:

Figure 1 Natural and introduced range of Mozambique tilapia baitfish and as protein for domesticated farm stock. It was because of their ability to efficiently convert a wide range of food introduced initially as an ornamental species into Indonesia and the material into protein. Bowen (1982) reviewed the literature on the USA then provided the basis for aquaculture in these countries. diets of 17 tilapiine species and found that O. mossambicus was Australia is the only country where the species was introduced among the most catholic in its feeding behaviour. While feeding exclusively for the aquarium trade (fig 2). predominantly on plant material, Bowen commented that ‘practically every aquatic animal, vegetable and mineral small enough to pass through the esophagus has been found in the guts of these fish’. O. mossambicus has been reported from its native and introduced range feeding on live aquatic and submerged terrestrial plants, benthic algae, phytoplankton, periphyton (algae attached to plants), zooplankton, and organic detritus (Hofstede & Botke 1950; Pannikar & Tampi 1954; Man & Hodgkiss 1977; Bowen 1978, 79, 80a, 81; Aravindan 1980; Dudgeon 1983; De Silva et al. 1984; De Silva 1985; Dickman & Nanne 1987; Blühdorn et al. 1990; Milward and Webb 1990; Webb 1994; Kim et al. 2002). Several studies have found free bacteria and cyanobacteria (Microcystis spp) to be a dominant or frequent component in the diet of juvenile and adult Mozambique tilapia (and tilapia) (Maitipe and De Silva 1985; Beveridge et al. 1989; Jameson 1991; Mol and van Der Lugt 1996; Komarakova and Tavera 2003). Bowen (1976, 1982) suggested that the ability of , such as O. mossambicus, to switch their mode of feeding (eg. from herbivory to detritivory or between phytoplankitivory to zooplanktivory) is related to incidental feeding. When deposit feeding, fish may ingest a mixture of sedimented phytoplankton, detritus and small invertebrates, eg., copepods, virtually indistinguishable to the diets of suspension feeders. O. mossambicus also undergoes ontogenetic change in feeding with a shift from macrophagy in fry and fingerlings (e.g., bacteria, , microcrustacea, rotifers) to predominantly macrophagy in adults (Vaas and Hofstede 1952; Le Roux 1956; Bowen 1976; Bowen & Allanson 1982). There have also been reports of O. mossambicus opportunistically feeding on other small fish and eggs (Riedel 1965; Eyeson 1983; Webb 1994) and aquatic macroinvertebrates, such as dipteran larvae (Legner and Medved 1973; Legner et al. 1980),

Figure 2 Tilapia in North Queensland Diet Maclean (1984) aptly described tilapias as ‘aquatic chickens’ >3< Reproduction

molluscs (Makoni et al. 2005) and winged (terrestrial) formicids arenas. These arenas consist of shallow circular pits excavated by (Bowen 1982). has also been reported in using the mouth as a bulldozer. Males defend these sites that are oreochromids including O. mossambicus though mainly under used only for mating and brief oviposition, and are not used for unnatural conditions such as aquaria and culture ponds (Neil 1966; rearing offspring (Baerends & Baerends-van Roon 1950; Fryer & Iles Macintosh & de Silva 1984; Panastico et al. 1988; Milward & 1972; Bruton & Boltt 1979). After fertilisation, the female Webb 1990). mouthbroods the eggs, larvae and fry at sites away from the arenas (Fryer & Iles 1972). The fry are released at the swim-up stage when Reproduction the swim bladder develops and, for a period of time, if danger O. mossambicus has a polygynous mating system resembling that threatens, they swim back into the bucca of other lekking , where males aggregate to form courtship l cavity of the female for protection. (or perception of individual's high status by neighbours that reduce Among with this mating system sexual differences in likelihood of incursions), that features associated with the size (dimorphism), colour (dichromatism) and other reproductive spawning site such as weeds or rocks - and the form of the pit - may behaviours are prevalent (Fryer & Iles 1972; Trewevas 1983) and are be attractive by providing protection from egg-stealing intruders. under hormonal control. Oliveira and Almada (1998a) proposed If the conspecific is a female showing the right colour-pattern and that androgens (male sex hormones) not only play an important behaviour (normal swimming without threat displays) the resident role in the expression of male secondary sex characters, but also as male will lead the female to the spawning pit where courthship mediators of social status (dominance), i.e., the expression of displays may occur or directly to spawning. The female lays a batch outcomes of male-male competition. Males therefore regulate their of eggs in the pit and immediately turns to pick them up. The male morphological and behavioural characters according to their swims over the same ground, emitting sperm, while the female resource-holding potential. This hormonal expression of traits has effects fertilisation in the mouth by snapping at the milt cloud an amplifier effect through positive feedback mechanisms, where (Baerends and Baerends-van Roon 1950; Trewevas 1983). initial differences in resource-holding potential may result in The aggressive and reproductive behaviour of adult males was increasingly larger differences in status during the spawning analysed and was, initially, found to be strongly influenced by the period. fishes' relative sizes. Towards the end of the study period, true size At sexual maturation, males are much larger than females in several became less important in affecting such behaviour than the initial morphological traits (body size, dorsal fin height, anal fin height, size, suggesting that there was a persistent effect of previous mandible width and premaxilla length). Bruton and Boltt (1979) interactions. The initial and final sizes of males were found to be described the first sign of breeding activity in Lake Sibaya, South negatively correlated, suggesting that one cost of territorial Africa, where males gathered offshore in schools at the surface and reproductive behaviour is reduced growth. began to adopt the black nuptial colouration. Schools then moved inshore to the shallow littoral terraces of the lake where males Factors Influencing Reproductive Behaviour: compete among themselves for acquisition and maintenance of Sound reproductive territories (Oliveira and Almada 1998b).Those males Acoustic emissions in this species may play a role in advertising the higher in the social hierarchy, besides having higher androgen presence and spawning readiness of males and in synchronising levels and gonadosomatic indexes, are more effective at defending male-female gamete release (Amorim et al. 2003, Amorim & territories, build larger display pits and court at a higher rate Almada 2005). In the initial phase of establishing male hierarchies, (Turner 1986; Oliveira et al. 1996). Mating success is strongly only territorial males produce sounds. These occur during male- skewed toward dominant territorial males in established groups male agonistic interactions and pit-related activities such as (Oliveira and Almada 1998c). digging and hovering, and at all phases of courtship, especially Contests between male O. mossambicus are usually settled on the during the later stages, including spawning. Winners of male basis of size and therefore likely related to strength and the contests make more courtship sounds than losers and the sounds resource-holding potential of the individual (Turner and are of longer pulse duration and lower peak frequencies than those Huntingford 1986; Turner 1994). Male aggression may take several made by losers (Amorim et al. 2003). forms of increasing intensity (Table 1). Intruding fish, if smaller Lanzing (1974) found that sounds are produced by stridulation of than the resident, are usually chased out of a territory and typically the pharyngeal teeth achieved by contraction of mandibular and involves circling, lateral displays that escalate to physical contact sonic musculature associated with the swim bladder. Dominant with lunging and ramming (Turner 1994). Boundary disputes males have much heavier jaw muscles than do subordinates as well occur frequently between adjacent territory holders. These fights as higher androgen levels (Oliveira 1995 in Amorim & Almada involve frontal displays which rarely result in a clear outcome and 2005). The difference in sounds produced by dominant males may are probably used mainly to fix the position of the territorial be related to greater mass of jaw musculature, in turn related to borders (Turner and Huntingford 1986). their higher levels of androgens, or to the transient effects of elevated hormone levels on muscle contraction in the jaws of Mate choice dominant male winners compared to losers. These sounds According to Nelson (1995), because O. mossambicus females are therefore may signal successful recent social experience of males, not herded by a dominant male and fertilisation is external, they and to increase mate attraction and influence mate choice (Amorim maintain a great deal of control over which males are et al. 2003; Amorim & Almada 2005). reproductively successful. Nelson found that females assessed both spawning site and male characteristics: they preferred the larger of interacting males, and males that produced larger-sized spawning pits. Also, the larger and more dominant males more often held territories in the more sheltered areas, which were favoured by all males, and which seemed to lead to greater courtship success (Turner 1986). This suggested that the position of the territory is also important. Combined with a male's ability to maintain tenure >4< Reproduction & Ecological Tolerances

Temperature (Wohlfarth et al. 1983; Behrends et al. 1990; Cnaani et al. 2000; Cai The major regulating factor in gonadal development in tilapias, as et al. 2004). in other warmwater fishes, appears to be temperature. During the colder months, spermatogenesis in males may be slowed down and Temperature vitellogenesis in females completely inhibited, ie., the spawning O. mossambicus is a warmwater, stenothermal species: though threshold appears more to be related to temperature effects on potential habitat it can occupy is restricted only by a limited gonad development in females than in males (Dadzie 1969; Moreau tolerance of low temperature (Hickling 1963). Lower lethal 1982; Jalabert and Zohar 1982). During cold periods in marginal temperatures between 8 and 15°C have been reported (Smit et al. environments, vitellogenesis may be completely inhibited in female 1981; Philippart & Ruwet 1982). The species has a thermal ‘zone of tilapia, and all yolk-laden oocytes disappear from the ovaries. In tolerance' between 15° and 37°C, and a limited tolerance of males, however, spermatogenesis, although greatly retarded, may temperatures between 39 and 40°C, with lethal temperatures at 41- be continuous with all development stages present in the testis. 42°C (Philippart & Ruwet 1982; Stauffer 1986). Subasinghe (1986) reported a lower thermal tolerance limit for Studies have shown that O. mossambicus and other tilapiine zygote development in laboratory populations of O. mossambicus can tolerate lower temperatures in saline than in fresh of between 17 and 20°C with less than 60% development at 20°C, water (Allanson et al. 1971; Chervinski and Lahar 1976) and occur although the optimal temperature range (>90%) development more frequently in than in towards the limit of occurred between 24°C and 34.5°C. Gender difference in gonadal their range (Knaggs 1977; Whitfield and Blaber 1979). In eastern maturation may be related to the species' lekk breeding system, Africa, the Pangola River (27° S lat.) is the southern limit of the especially in aseasonal populations when mature males change to species in fresh water. However, the species has extended its range breeding colours and aggregate in shallow margins to establish by inhabiting estuaries and coastal lagoons as far south as Port courtship display territories prior to females reaching spawning Elizabeth, Algoa Bay, in Cape Province, South Africa (33° 50' S condition. lat.) (Whitfield & Blaber 1979). The known southern limit of the Also, as tilapias are multiple spawners, the number of spawnings is species in Queensland is around Brisbane (27° 26' S lat.) similar to dependent on temperature and therefore on latitude and altitude the species' limit in . In comparison with its range (Philippart and Ruwet 1982). In higher latitudes and altitudes, the extension in southern Africa, in saline waters, O. mossambicus may spawning season is restricted to 3 to 5 months ie. between 2 to 5 be able to survive in estuaries as far south as Sydney, NSW (33° 53' spawning cycles (Hodgkiss & Man 1978; James & Bruton 1992), S lat.). while in tropical and equatorial areas spawning may be continuous, While its ecological attributes are unknown, the northern or close to it, throughout the year (Philippart and Ruwet 1982). Queensland hybrid O. mossambicus has genes from O. niloticus Ecological studies on populations of Oreochromis spp distributed and O. aureus (Mather and Arthington 1991). O. niloticus hybrid over latitudes from about 33N to south of the equator show a strains were developed to produce fish with superior growth change from seasonal to aseasonal breeding with decreasing characteristics and appearance (colour) (Bentsen et al. 1998; latitude. The transition to seasonal breeding occurs approx. Garduno-Lugo et al. 2003), while O. aureus is used to produce between latitudes 8° and 18° north and south of the equator. The cold-tolerant strains of tilapia, including O. mossambicus hybrids breeding season is influenced by regional differences in climate, (Behrends and Smitherman 1984; Cnaani et al.2000). being extended for as long as water temperature is favourable. Salinity The temperature threshold for spawning has been identified for The species is euryhaline and can live in fresh or brackish water several species of tilapia as occurring between 18° and 24°C (Watanabe et al. 1985 & 1989; Jamil et al. 2004; Kamal et al.2005) (Cridland 1962; Miranova 1978; Terkatin-Shimony et al. 1980; and can survive in normal seawater (Lobel 1980) as well as Moreau 1982; Philippart and Ruwet 1982; Arthington and Milton hypersaline conditions (Potts et al.1967; Popper & Lichatowich 1975; 1986) and within a narrow band 1-2 degrees Celsius for individual Stickney 1986). Whitfield and Blaber (1979) reported the species species. James & Bruton (1992) reported that the spawning season survives in St Lucia Lake, an open estuarine-lake system in south- (start of maturation) of O. mossambicus in Eastern Cape, South eastern Africa, where it can tolerate gradual changes ranging from Africa usually commenced when minimum water temperatures 0 to 120 ppt (see also Potts et al. 1967; Assem & Hanke 1979). O. exceeded 18C. In south eastern Queensland (approx. 27° S. lat.) mossambicus adults and juveniles can also survive direct transfer to Arthington & Milton (1986) reported a temperature threshold for 20 ppt (Hwang 1987), but not to 30ppt without an acclimation spawning in O. mossambicus of 23°-24°C and a spawning season period at 20ppt. Lin et al. (2001) found that O. mossambicus fry over 5-6 months. In tropical northern Queensland (Townsville: 19° could also survive direct transfer from 32ppt to fresh water. S. lat.), Webb (1994) found a similar spawning threshold (23°C) for Spawning of O. mossambicus has been reported in salinities O. mossambicus but the species was almost an aseasonal spawner ranging from 0-49 ppt (see Stickney 1986) and Uchida and King (9-10 months), with peak spawning over a period of about four to (1962) indicated that fry production was three times higher in slight five months. Based on average surface water temperature data, saline (brackish) waters of 10ppt than in fresh water. O. Webb noted that a relatively small average increase in water mossambicus also shows enhanced growth in brackish water temperatures (<1.5°C), similar to those found for shallow waters conditions compared with high or very low salinities and in fresh northward from Cairns (16.5° S lat.) could result in average surface water (Uchida and King 1962; Canagaratnam 1966; Bashamohideen & water temperatures in the Townsville region being above 23°C in Parvatheswararao 1972) and may be physiologically related to O. all months and probably allow continuous breeding. mossambicus also shows enhanced growth in brackish water conditions compared with high or very low salinities and in fresh Ecological tolerances water (Uchida and King 1962; Canagaratnam 1966; Bashamohideen & O. mossambicus is a remarkably hardy species and its success in exploiting new and diverse habitats has been attributed, in part, to its tolerance of a wide range of environmental conditions. Hybridisation of oreochromid tilapias has produced strains with enhanced growth characteristics and environmental tolerances including to low temperature, overcrowding stress and pathogens

>5< Ecological Tolerances & Ecological Impacts

Parvatheswararao 1972) and may be physiologically related to even reported long term survival of the species buried in a layer of osmoregulatory function at these salinities (Canagaratnam 1966). moist sand in a ‘dry' river bed! A number of studies have also demonstrated that O. mossambicus hybrids (as well as other tilapiine hybrids) exhibit enhanced salinity Ecological impacts tolerance, growth and reproductive performance across a range of Interference competition experimental salinities compared with parental stock (see Stickney Studies have demonstrated that overcrowding by exotic fishes, 1986; Watanabe et al. 1985; Watanabe et al. 1989; Kamal et al. including tilapias, can have debilitating effects on native species 2005). (Cahoon 1953; Noble et al. 1975; Forester and Lawrence 1978; Taylor et al. 1984). Significant decreases in the size of native fishes pH caught and overall contribution to fish production in several lakes The species can also tolerate extremes of acidity and alkalinity, with and reservoirs in India and Sri Lanka were reported following the pH values ranging between 3.7 and 10.3 (Krishna Murthy et al. 1981; introduction of O. mossambicus (Natarajan 1971; de Silva 1988; Bhaskar and Govindappa 1985a, 1985b,19 86a & 1986b; van Ginneken et al. Bhagat and Dwivedi 1988). In these studies, the species (or other 1997; Leghari et al. 2004). Swingle (1961) reported for O. introduced tilapias) eventually dominated communities, in some mossambicus an alkaline lethal limit of pH 11 and Krishna Murthy cases, up to 99% of the fish population. However, while declines et al. (1984) and acidic lethal limit of pH 3.4. were attributed to the introductions, they were not investigated to determine their cause. Pollution Both male and female O. mossambicus are territorial and Studies have demonstrated that O. mossambicus has a remarkable aggressive during the spawning season. Morgan et al. (2004) tolerance for organically polluted waters (e.g. Gaigher & Krause 1983; reported that large O. mossambicus males in the Gascoyne River, Wrigley 1988; Kumta et al. 1998; Noorjahan et al. 2003); and those Western Australia, excluded native species from large stretches of contaminated by inorganic pollution (e.g. Huang Yuyao et al. 1989; the river. They suggested that such exclusion "must have a serious Panigrahi & Konar 1992; Subramanian & Manickavasakam 1993; Chen et deleterious effect on the native fishes" (p.521) especially in dry al. 2001; Nanda et al. 2002; Somanath 2003). conditions when rivers are reduced to disconnected, small pools, although they did not quantify these effects. A study by Fuselier Nitrogen/ammonia (2001) demonstrated that O. mossambicus, following introduction O. mossambicus can tolerate levels of nitrogen or ammonia that into lakes in Mexico, caused major declines in populations of can inhibit growth or be lethal to many Australian native fishes. endemic pupfishes. The presence of O. mossambicus caused a Sampath et al. (1991) reported 100% survival of O. mossambicus at displacement of these fishes into marginal habitats resulting in 14 mg N/L while LC50 for 96hr exposure was 32 mg/ nL. The increased agonistic interactions among pupfish species, limiting species also tolerates ammonia stress up to 3 mg/NL without their access to food resources and therefore experiencing sub- significant reduction in food intake or growth. This contrasts with optimal conditions for survivorship. Fuselier warned that these hyper-tolerant species e.g. the snakehead, Channa striata, which pupfish flock species may be threatened with where can survive in ammonia concentrations between 10.7 and 52 mg/l habitat displacement by O. mossambicus could result in a (Murugesan & Parameswaran 1977; Sampath 1985) and the breakdown of premating segregation mechanisms of sympatrics majority of more sensitive species, such as salmonids which can followed by genetic introgression and loss of rare phenotypes. only tolerate low ammonia levels (0.5 mg/l) (Larmoyeux & Puiper 1973; Liao & Mayo 1974). Pearson et al. (2003) detected sublethal Grazing and habitat impacts effects for fingerling barramundi and snails (Physa sp.) at quite low Lahser (1967) reported that O. mossambicus killed aquatic concentrations of NH3. Feeding of barramundi was suppressed for macrophytes while feeding on periphyton such as diatoms, several days following exposure to 0.08-0.19 mg N/L NH3. Snails filamentous algae and cyanobacteria. Leaves, stems and roots were exhibited avoidance behaviour (emergence from water) when scraped or rasped to shreds; the plants were killed and consumed exposed to 0.19 mg N/L NH3. Changes in colour and swimming secondarily. Field observations by Lahser showed that O. activity of fingerling barramundi were evident at 0.37-0.52 mg N/L mossambicus eliminated several species of submerged and NH3. Lethal effects on fingerling barramundi and small size emergent macrophytes, either by grazing or by uprooting plants. classes of rainbowfish were observed at 0.56-0.75 mg N/L of NH3. Lahser also observed increased turbidity in shallower margins due Medium and large size classes of rainbowfish exhibited sublethal to the activity of male fish clearing areas for courtship display pits effects (increased swimming activity, aquatic surface respiration) at that subsequently resulted in further loss of photosynthetic 0.57-0.75 mg N/L of NH3, but did not experience mortality until production. Cooper and Harrison (1992) suggested that under exposed to 0.97-1.08 mg N/L of NH3. certain circumstances, for example, where there are very large populations of fish present, pit excavations by adult male O. Hypoxia (low dissolved Oxygen) and desiccation mossambicus could also significantly change natural erosion O. mossambicus can tolerate low dissolved oxygen concentrations patterns, increasing bank instability and loss of marginal of 0.1ppm for short periods (Maruyama 1958). Studies by vegetation, which in turn can locally influence the allochthonous Rappaport et al. (1976) found that growth in tilapia was reduced energy budget (nutrient inputs) of a waterbody and loss of below 25% oxyegen saturation and mortality occurred when oxygen important habitat for native species. remains below 20% saturation for more than 2 to 3 days. At low oxygen concentrations, tilapia can use aquatic surface respiration (i.e. irrigating the gills with the surface layer of water where oxygen exchange with the atmosphere occurs) (Senguttuvan & Sivakumar 2002) if access is not restricted e.g., by floating vegetation (Stickney et al. 1977). There have been reports of the species surviving in small muddy pools for several days with little ill effect (Chervinski 1982). Bakthavathsalam (1988, 2003) found that O. mossambicus, is a facultative air-breather and, depending on air temperature, can survive complete air exposure for several hours. Donnelly (1978) >6< Ecological Impacts

Predation in its introduced range (Blühdorn et al. 1990; Webb 1994 & 2007; There are few reports that document the extent of impacts of Mol and Van Der Lugt 1996; Morgan et al. 2004) although usually predation by O. mossambicus on other fish populations. Fuselier with few species and with significant overlap. Guerrero (1999) (2001) reported O. mossambicus feeding directly on fish eggs and reported no overlap in diet between introduced tilapias (O. small endemic pupfish fish in a natural lake, contributing to mossambicus and O. niloticus) and endemic fishes in some population declines. Aravindan (1980) also reported that O. Philippine lakes and reservoirs. Piet and Guruge (1997) reported mossambicus, in open riverine waters, supplemented its diet with dietary overlaps between introduced O. mossambicus and O. fish eggs and small fry. Arthington and Blühdorn (1994) referred to niloticus and among these species and eight indigenous species in a unpublished observations by Arthington and Milton that analysis shallow Sri Lankan reservoir. However, they noted that temporal of fish diets from sub-tropical impoundments provided evidence resource partitioning occurred during feeding, while spatial that O. mossambicus consumes small forage fish (rainbowfish and partitioning occurred during non-feeding to avoid interference gudgeons) and that consumption of such fish and aquatic competition or predation. Blühdorn et al. (1990) reported resource invertebrates may be higher in waterbodies with low primary partitioning between O. mossambicus and a plotosid catfish productivity. (Tandanus tandanus) and Spangled perch (Leiopotherapon An experimental study by Dickman and Nanne (1987) indicated unicolor) in North Pine Dam, Queensland, even with changes in that tilapia hybrids (Oreochromis (Sarotherodon) mossambicus x water levels affecting food resources and their availability. Morgan hornorum), similar to those that occur in the Cairns region, et al. (2004) suggested that there was little overlap in diet between northern Queensland, at high densities, negatively impacted on O. mossambicus and native fishes in the Pilbara region, Western water quality of culture ponds by predation on zooplankton. Australia, and that there was unlikely to be little competition for Cyanobacterial blooms occurred due to loss of grazing pressure on food except with one native species (Craterocephalus cuneiceps) primary consumers (copepods), resulting in night-time oxygen that had a similar diet to O. mossambicus: primarily benthic concentrations dropping close to zero percent saturation. It was detritus/biofilm, but also aquatic insects. Webb (1994) found an subsequently observed that, in the early morning, stressed fish overlap in diet of O. mossambicus with Bony bream in the Ross approached the surface to breathe, where dissolved oxygen River weirs and Ross Dam, Townsville. Both species are essential concentration in the water was highest. All fish in the ponds then or benthic feeding detritivores. became vulnerable to predation by piscivorous birds. Diana et al. (1996) found that another oreochromid, Oreochromis Disease niloticus, significantly reduced zooplankton in ‘eutrophic’ culture Introduced fish species are known to be important vectors of ponds, although this inhibition did not cascade down to lower disease agents such as viruses, bacteria and fungi as well as levels (i.e. primary production). It was suggested that the main metazoan parasites (Langdon 1990). In Australia: Carp, Redfin effect (zooplankton reduction) was due largely to resource perch, Goldfish and salmonids have been responsible for the limitation in small ponds rather than effects caused by fish. Studies introduction of several pathogens, some of which have adversely using other fish species in larger oligotrophic and mesotrophic impacted native fishes, or have been detected in quarantine lakes found similar results (Scavia et al. 1986; McQueen et al. 1986; (Ashburner 1976, Langdon 1987, 1988, 1989). Disturbingly, Evans Vanni 1987; Mazumder et al. 1988). A study by Starling et al. (2002) and Lester (2001) found that fish parasites are continuing to enter found that large populations of two introduced tilapiine cichlids, Australia. They reported 10 metazoan parasites, including non Tilapia rendalli and Oreochromis niloticus, significantly host-specific species, on imported non-native fishes - even after a contributed to cyanobacterial blooms in a Brazilian reservoir, period of quarantine. These parasites included specialist and where cyanobacterial growth was due to enhanced phosphorus generalist parasites known to cause serious pathology, notably the loading in the water through fish excretion, rather than reduction cestode, Bothriocephalus achielognathi and the , in zooplankton inhibition. The eutrophic conditions resulted in Camallanus cotti, already transmitted to native fishes as they are hypoxia caused by cyanobacterial respiration that was followed by non-specific for their intermediate hosts (copepods). massive fish kills in the reservoir. These studies demonstrate that There are several reviews of diseases of tilapias, mainly those in changes in trophic structure of local communities following aquaculture (Paperna 1974 & 1980; Roberts and Sommerville 1982, introductions of tilapiine cichlids, including Oreochromis Paperna et al.1983; Michel 1989). The only known parasite infecting mossambicus, can be complex and not always predictable. native fishes attributable to the introduction of O. mossambicus is the ciliate protist, Trichodina heterodentata (Dove 1999; Dove and Competition for food O'Donoghue 2005). Although the impact on native fishes has not Few studies have examined whether changes in food resources been documented, trichodinids are known to cause serious injury following introduction of tilapias have significantly impacted and death, usually where fish are stressed or there are high host directly on survivorship of native herbivorous, zooplankitovorous densities, as in culture conditions (Lentinen et al. 1984; Barker et or even piscivorous species, including different life stages (fry, al. 2002; Khan 1991). Webb (2003) reported the introduced cestode, juveniles and adults). Fuselier (2001) noted that aggressive B. achielognathi, from O. mossambicus and the Guppy, Poecilia displacement and decline of endemic lake pupfish by O. reticulata, from a single location near Cairns. This parasite was mossambicus was partly due to prevention of access of pupfish to introduced into Australia on Carp (Dove et al.1997), but Guppies normal food resources. Sreenivasan (1967) and Ranoemihardjo and other poeciliids are also known as vectors (Font and Tate (1981) reported that O. mossambicus inhibited growth of milkfish 1994; Font 1997a,b). This is the first report of B. acheilognathi in culture ponds due to competition for food, while Jhingran (1992) from O. mossambicus and its first reported that native Mugil spp. in Indian reservoirs were displaced by O. mossambicus and carps through competition for food. Displacement through competition for food of native fishes following introduction of tilapias have been reported in Indonesian (Hardjamulia and Wardogo 1991) and Mexican lakes (Juarez- Palacios and Olmos-Tomassini 1991). A number of studies, mainly of adult fishes, have shown dietary overlap between O. mossambicus and other fish species occurring >7< Ecological Impacts, Glossary & References reported occurrence in northern Queensland. This is of particular of the parasite to native fishes in northern Queensland, or the interest as this parasite has been responsible for mass fish kills in pathological effect of the parasite on tilapiine hosts). Rocke et al. Australia (Dove 1999) and overseas in other parts of the introduced (2005) reported major die-offs of pelicans on the Salton Sea, USA, range of cyprinids (e.g.Granath and Esch 1983; Font and Tate due to botulism. These researchers suggested that pelicans were 1994; Heckmann 2000). Further research is needed to determine infected after feeding on tilapia which were carriers of the botulism the distribution of this parasite and the host-parasite relationship pathogen, Clostridium botulinum . with O. mossambicus (or T. mariae) (i.e., tilapiine hosts as vectors

Glossary Allochthonous Organic matter originating from outside the community (eg. Oligotrophic A lake or waterbody which is poor in dissolved nutrients and from terrestrial / riparian vegetation) usually rich in dissovled oxygen, and contain little Anal (Fin) beneath the body, behind anal opening or animal life Benthic Related to the bottom of waterbody Ontogenetic Pertaining to the origin or development of an organism from Buccal Related to the cheeks or cavity of the mouth embryo to adult Cannibalism Predation of an animal by a member of its own species Opercular Situated near or related to the gill cover Caudal Towards the tail. Osmoregulator Control of the water and electrocyte balance in the body Concave Hollowed out, curving inward like the inside of a spoon y Dichromatism Sexual differences in colour Oviposition To lay eggs, by means of an ovipositor (a tubular structure) Dimorphism Sexual differences in size Pharyngeal Related to or coming from the pharynx: the part of the neck and Dorsal Situated near to or on the back throat situated immediately posterior to the mouth and nasal Endemic Native to or confined to a certain region cavity Euryhaline Fish that live in a wide range of salinities, opposite to Phenotypes The observable characteristics of an individual stenohaline Piscvorous Fish-eating or fish-egg-eating Fry Newly hatched or born fish Polygynous Multiple partner Gonad The sex gland that make sex cells. These are ovaries in the Premaxilla A pair of small cranial bones at the very tip of the jaws of many female and testes in the male. animals, usually bearing teeth, but not always. Gonadosomati GSI = (testis weight / body weight)x100 Spermatogene Formation and development of spermatozoa (the mature sperm c indexes sis cell) by meiosis and spermiogenesis Herbivorous Plant eating Stenothermal It can tolerate a limited range of temperatures, opposite to Hypoxia An inadequate supply of oxygen to the tissues. eurythermal Introgression Movement of a new gene into a population Stridulation To produce a shrill grating, chirping or hissing sound by Lateral Situated at or extending to the side rubbing body parts together. Littoral A coastal region, shore, the zone between the limits of high and Stunting Fish whose growth is severely hampered by environmental low tides, lake margins. Equates to approximately the euphotic factors such as overpopulation zone: the depth range at the margins where photosynthesis can Sympatrics Sympatry is one of four theoretical models for the phenomenon occur. of speciation. Macrophagy Feeding on large particulate matter Transient Passing with time, transitory Mandible The lower jaw Vitellogenesis Yolk deposition, or the process of nutrients being deposited in Mesotrophic A lake or waterbody of moderate photosynthetic productivity oocytes: a female germ cell involved in reproduction Oocytes A female germ cell involved in reproduction Zygote A fertilised egg before cell division begins

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Jameson, J.D., 1991. Plankton feeding habit of Oreochromis mossambicus (Cichlidae) held in cages, in Sathiar Reservoir, Tamil Nadu. Comparative Physiology and Ecology 16(2): 72-75. Legner, E.F. and Medved, R.A. and Pelsue, F., 1980. Changes in chironomid breeding patterns in a paved river channel following adaptation cichlids of the Tilapia mossambica-honorum complex. Entomological Society of America 73(3): 293-299. Jamil K., Shoaib M., Ameer F . and Lin, H., 2004. Salinity tolerance and growth response of juvenile Oreochromis mossambicus at different salinity levels. Journal of Ocea University of China Oceanic and Coastal Sea Research 3(1): 53-55. Lentinen K-J., Notini M. and Landner L., 1984. Tissue damage and parasite frequency in flouders, Platichthys flesus (l.) chronically exposed to bleached kraft pulp mill effluents. Annales Zoologici Fennici 21(1): 23-28. Jhingran A.G., 1992.Performance of tilapia in Indian waters and its possible impact on the native ichthyofauna. FAO Fisheries Reports 458 (Supplement). FAOUN, Rome. Liao P.B. and Mayo R.D., 1974. Intensified fish culture combining water reconditioning with pollution abatement. Aquaculture 3: 61-85. Juarez-Palacios J.R. and Olmos-Tomassini M.E., 1991. Tilapia capture in Latin America. In: E.A. Baluyut (ed): Indo-Pacific Fishery Commission, country reports presented at the Fifth Session of the Indo-Pacific Fisheries Commission Working Party of Experts on Inland Fisheries, Lin L-Y., Weng C-F. and Hwang P-P., 2001. Regulation of drinking rate in euryhaline tilapia larvae Bogor, Indonesia, 24-29 June 1991, FAO Fisheries Report No. 458 (Suppl.). FAO, Rome, 244- (Oreochromis mossambicus) during salinity changes. Physiological and Biochemical Zoology 273. 74(2): 171-177.

Kamal A.H.M. and Mair G.C., 2005. Salinity tolerance in superior genotypes of tilapia, Lobel P.S., 1980. Invasion by the Mozambique tilapia (Sarotherodon mossambicus; Pisces: Oreochromis,Oreochromis mossambicus and their hybrids. Aquaculture 247(1-4): 189-201. Cichlidae) of a Pacific atoll marine ecosystem. Micronesia 16(2): 349-355.

Khan R.A., 1991. Mortality in Atlantic (Salmo salar) associated with trichodinid ciliates. Journal of Wildlife Diseases 27(1): 153-155.

Kim, H.C., Lee, J.H., Yang, K.H. and Yu, H.S., 2002. Biological control of Anopheles sinensis with native fish predators (Aplocheilus and Apphyocypris) and herbivorous fish, Tilapia, in fields in Korea. Korean Journal of Entomology 32(4): 247-250. >10< References

Macintosh, D.J. and de Silva, S.S., 1984. The influence of stocking density and food ration on fry Noorjahan C.M., Dawood S.S. and Nausheen D. 2003. Impact of dairy effluent on biochemical survival in Oreochromis mossambicus and O. niloticus female x O. aureus male hybrids reared constituents of fish Oreochromis mossambica. Journal of Ecotoxicology & Environmental in a closed circulated system. Aquaculture 41(4): 345-358. Monitoring 13(3): 227-231

Maclean, J., 1984. Tilapia - the Aquatic Chicken. ICLARM Newsletter 7(1): 17. Oliveira, R.F. and Almada, V.C., 1998a. Androgenization of dominant males in a cichlid fish: androgens mediate the social modulation of sexually dimorphic traits. Ethology 104: 841-858.

Maitipe, P. and De Silva S.S., 1985. Switches, between, phytophagy, zoophagy and detritivory of Sarotherodon mossambicus (Peters) populations in twelve man-made Sri Lankan lakes. Oliveira, R.F. and Almada , V.C., 1998b. Dynamics of social interactions during group formation in Journal of Fish Biology 26: 49-61. males of the cichlid fish Oreochromis mossambicus. Acta Ethologica 1(1-2):57-70.

Makoni, P., Chimbari, M.J. and Madsen, H., 2005. Interactions between fish and snails in a Oliveira, R.F., Almada, V.C. and Canario, A.V.M., 1996. Social modulation of sex steroid Zimbabwe pond, with particular reference to Sargochromis codringtonii (Pisces: Cichlidae ). concentrations in the urine of male cichlid fish Oreochromis mossambicus. Hormones and African Journal of Aquatic Science 30(1): 45-48. Behaviour 30(1): 2-12.

Man, H.S.H. and Hodgkiss, I.J., 1977. Studies on the ichthyofauna in Plover Cove Reservoir, Hong Oliveira, R.F. and Almada , V.C., 1998c. Mating tactics and male-male courtship in the lek-breeding Kong . Journal of Fish Biology 11(1): 1-13. cichlid Oreochromis mossambicus Journal of Fish Biology 52(6), June 1998:1115-1129.

Maruyama T., 1958. An observation on Tilapia mossambica in ponds referring to the diurnal Panastico, J.B., Dangilan, M.M.A. & Eguia, R.V., 1988. Cannibalism among different sizes of movement with temperature change. Bulletin of the Freshwater Fisheries Research tilapia (Oreochromis niloticus) fry/fingerlings and the effect of natural food. In: R.S.V. Pullin, Laboratory, Tokyo . 26(1): 11-19. K. Bhukaswan, K. Tonguthai and J.L. Maclean (eds): The Second International Symposium on Tilapia in Aquaculture. ICLARM Conference Proceedings No. 15. ICLARM, Manila , Philippines, 465-468. Mather P.B. and Arthington A.H., 1991. An assessment of genetic differentiation among feral Australian Tilapia populations. Australian Journal of Marine and Freshwater Research 42(6): 721-728. Panigrahi A.K. and Konar S.K., 1992. Influence of petroleum refinery effluent in presence of nonionic detergent sandozin NIS on fish. Environment and Ecology (Kalyani) 10(1): 55-59.

Mazumder A., McQueen D.J., Taylor W.D. and Lean D.R.S., 1988. Effects of fertilisation and planktivorous fish (yellow perch) predation on size distribution of particulate phosphorous: Paperna I., 1974. Lymphocystis in fish from East African Lakes. J. Wildlife Diseases, 9: 331-335. large enclosure experiments. Limnology and Oceanography 33: 421-430.

Paperna I., 1980. Parasites, infections and diseases of fish in Africa. CIFA technical paper No. 7, McQueen D.J., Post J.R. and Mills E.L., 1986. Trophic relationships in freshwater pelagic FAO, Rome . ecosystems. Canadian Journal of Fisheries and Aquatic Science 43: 1571-1581.

Paperna I., Van As J.G. and Basson L., 1983. Review of diseases affecting cultured cichlids. In: L. Michel C., 1989. Pathology of tilapias. Aquatic Living Resources 2: 117-126. Fischelson and Z Yaron (eds): International Symposium on Tilapia in Aquaculture. Tel Aviv University, Nazareth, 174-184.

Milward, N.E. and A.C. Webb, 1990. The Status of the Introduced Tilapia Species Oreochromis mossambicus in the Townsville Region: Distribution, Feeding and Reproduction. A report to Pearson R.G., Crossland M., Butler B. and Manwaring S., 2003. Effects of canefield drainage on the Townsville City Council. Zoology Department, James Cook University of North the ecology of tropical waterways. ACTFR Report No.03/04. Australian Centre for Tropical Queensland, Queensland. Freshwater Research, James Cook University, Townsville, Australia.

Mironova, N.V., 1978. Energy expenditure on egg production in young Tilapia mossambica and the Philippart, J.-C. and Ruwet, J.-C., 1982. Ecology and distribution of tilapias. In: Biology and Culture influence of maintenance conditions on their reproductive intensity. Journal of Ichthyology 17: of Tilapias (Pullin, R.S.V. and Lowe-McConnell, R.H., eds.). ICLARM, Manila, Philippines, 627-633. pp. 15-59.

Mol, J.H. and Van der Lugt, F.L., 1996, Distribution and feeding ecology of the African tilapia Piet G.J. and Guruge W.A.H.P., 1997. Diel variation in feeding and vertical distribution of ten co- Oreochromis mossambicus (Teleostei, Perciformes, Cichlidae) in Suriname () occurring fish species: consequences for resource partitioning. Environmental Biology of with comments on tilapia-kwikwi (Hoplosternum littorale) (Teleostei, Siluriformes, Fishes 50(3): 293-307. Callichthyidae) interaction. Acta Amazonica 25(1-2): 101-115.

Popper D. and Lichatowich T., 1975. Preliminary success in predator control of Tilapia mossambica. Moreau, J., 1982. Etude du cycle reproducteur de Tilapia rendalli et Sarotherodon macrochir dans Aquaculture 5(2): 213-214. un lac tropical d'altitude: le lac Alaotra (Madagascar). Acta Oecologia Appl. 3: 3-22.

Potts W.T.W., Foster M.A., Rudy P.P. and Howells G.P., 1967. Sodium and water balance in the Morgan D.L., Gill H.S., Maddern M.G. and Beatty S.J., 2004. Distribution and impacts of cichlid teleost, Tilapia mossambica. Journal of experimental Biology 47: 461-470. introduced freshwater fishes in Western Australia. New Zealand Journal of Marine and Freshwater Research 38: 511-523. Ranoemihardjo B.S., 1981.Eradication of tilapia from fresh - and brackishwater lagoons and ponds with a view to promoting milkfish culture . A report prepared for the Nauru Tilapia Murugesan V.K. and Parameswaran S., 1977. Observations on the transportation of murrel seed Eradication, Project Field Document 1,FAO, Rome. under oxygen packing. Mysore Journal of Agricultural Science 11: 199-21.

Rappaport A., Sarig S. and Marek M., 1976.Results of tests of various aeration systems on the Nanda P., Nath D. P. and Behera M.K., 2002. Respiratory metabolism of fish Oreochromis oxygen regime in Genosar experimental ponds and growth of fish there in 1975. Bamidgeh mossambicus (Peters) exposed to pulp and paper mill effluents. E nvironment and Ecology 28(3): 35-49. (Kalyani) 20(3): 570-572.

Riedel, D., 1964. Some remarks on the fecundity of tilapia (Tilapia mossambica Peters) and its Natarajan J., 1971.Workshop on ecology and fisheries of freshwater reservoirs. CFRI, Barrackpore, introduction into middle central America (Nicaragua). Hydrobiologia 25: 357-388. Aug 1971: 30-31.

Roberts R.J. and Sommerville C., 1982. Diseases of Tilapias. In: The biology and culture of tilapias Neil, E.H., 1964. An analysis of colour changes and social behaviour of Tilapia mossambica . (Pullin, R.S.V. and Lowe McConnell, R.H., eds.). ICLARM, Manila, Philippines, 247-267. University of California Publ. Zool. 75: 1-58. Panikkar, N.K. and Tampi, P.R.S., 1954. On the mouth-breeding cichlid, Tilapia mossambica Peters. Indian Journal of Fisheries 1: 217-230. Rocke T., Converse K., Meteyer C. and MacLean B., 2005. The impact of disease in the American White Pelican in . Waterbirds 28(Special Publication 1): 87-94. Nelson, M.C., 1995. Male size, spawning pit size and female mate choice in a lekking cichlid fish. Animal Behaviour 50: 1587-1599. Sampath K., Sivakumar V., Sakthivel M., and James R., 1991. Lethal and sublethal effects of ammonia on survival and food utilization in Oreochromis mossambicus (Pisces: Cichlidae). Noble R.L., Germany R.D. and Hall C.R., 1975. Interactions of blue tilapia and largemouth bass in Journal of Aquaculture in the Tropics 6(2): 223-230. a power plant cooling reservoir. Proceedings of the Annual Conference of the Southeastern Association of Game and Fish Commissioners 29: 247-251.

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Scavia D., Fahnenstiel G.L., Evans M.S., Jude D.J. and Lehman J.T., 1986. Influence of salmonid Turner G.F., 1986. Territory dynamics and cost of reproduction in a captive population of the predation and weather on long-term water quality trends in Lake Michigan. Canadian Journal colonial nesting mouthbrooder Oreochromis mossambicus (Peters). Journal of Fish Biology of Fisheries and Aquatic Science 43: 435-443. 29: 573-587.

Senguttuvan M. and Sivakumar A.A., 2002. Effect of air - exposure on the blood parameters of Turner G.F., 1994. The fighting tactics of male mouthbrooding cichlids: the effects of size and Oreochromis mossambicus (Peters). Himalayan Journal of Environment and Zoology 16(1- residency. Animal Behaviour 47: 655-662 2):15-21.

Turner G.F. and Huntingford F.A., 1986. A problem for game theory analysis: assessment and Smit G.L., Hattingh J. and Ferreira J.T., 1981. The physiological responses of blood during thermal intention in male mouthbrooder contests. Animal Behaviour 34: 961-970. adaptation in three freshwater fish species. Journal of Fish Biology 19(2): 147-160.

Uchida R.N. and King J.E., 1962. Tank culture of tilapia. Fisheries Bulletin 62: 21-52. Somanath V., 2003 Impact of tannery effluent on bioenergetics of fishes. Journal of Ecotoxicology & Environmental Monitoring 13(3): 161-173. Vaas K.F. and Hostede A.E., 1952. Studies on Tilapia mossambica Peters (ikan mudjair) in Indonesia . Contributions of the Inland Fisheries Research Station, Djakarta, Bogor 1: 1-68. Sreenivasan A., 1967.Tilapia mossambica - its ecology and status in Madras State, India. Madras Journal of Fisheries 3: 32-43. van Ginneken V.J.T., van Eersel R., Balm P., Nieveen M. and van den Thillart G., 1997. Tilapia are able to withstand long-term exposure to low environmental pH, judged by their energy status, Starling F., Lazzaro X., Cavalcanti C. and Moreira R., 2002. Contribution of omnivorous tilapia to ionic balance and plasma cortisol. Journal of Fish Biology 51(4): 795-806. eutrophication of a shallow reservoir: evidence from a fish kill. Freshwater Biology 47(12: 2443- 2452. Vanni M.J., 1987. Effects of food availability and fish predation on a zooplankton community. Ecological Monographs 57: 61-88. Stauffer J.R. Jr., 1986. Effects of salinity on preferred and lethal temperatures of the Mozambique tilapia, Oreochromis mossambicus (Peters). Water Resources Bulletin 22(2): 205-208. Watanabe W.O., Kup C.-M. and Huang M.-C., 1985. The ontogeny of salinity tolerance in the tilapias , O. niloticus, and an O. mossambicus x O. niloticus hybrid, Stickney R.R., 1986. Tilapia tolerance of saline waters: a review. Progressive Fish Culturist 48(3): spawned in freshwater. Aquaculture 47(4): 353-367. 161-167.

Watanabe W.O., Burnett K.M., Olla B.L. and Wicklund R.I., 1989. The effects of salinity on Stickney R.R., Rowland L.O., and Hesby J.H., 1977. Water quality - Tilapia aurea interactions in reproductive performance of Florida red tilapia. Journal of the World Aquaculture Society ponds receiving swine and poultry wastes. Proceedings of the World Mariculture Society 8: 55- 20(4): 223-229. 71.

Webb A.C., 1994. Ecological aspects of the Mozambique mouthbrooder, Oreochromis Subasinghe, R.P., 1986. Studies on the effects of environmental factors and selected pathogens on mossambicus, and other introduced cichlids in northern Queensland. MSC thesis, Faculty of morbidity and mortality of hatchery reared Oreochromis mossambicus (Peters) eggs and fry . Biological Sciences, James Cook University, Townsville. PhD thesis, University of Stirling, Scotland.

Webb A.C., 2003.The ecology of invasions of non-indigenous freshwater fishes in northern Subramanian J. and Manickavasakam D., 1993. Effects of distillery effluent on some physiological Queensland. PhD thesis. School of Tropical Biology, James Cook University, Townsville, aspects of Cyprinus carpio var. communis and Oreochromis mossambicus. Journal of Queensland Ecotoxicology & Environmental Monitoring 3(2): 121-124.

Webb A.C., 2007. Status of the Mozambique tilapia, Oreochromis mossambicus, in the Ross Dam, Swingle H.S., 1961. Relationship of pH of pond waters to their suitability for fish culture. Townsville, in Tropical northern Queensland. A report for NQ Water. School of Marine and Proceedings of the Pacific Science Congress 9:1-4. Tropical Biology, James Cook University, Douglas, Qld, Australia.

Taylor J.N., Courtenay Jr. W.R. and McCann J.A., 1984. Known impacts of exotic fishes in the Wohlfarth G.W., Hulata G., Rothbard S., Itzkowich J. and Halevy A., 1983. Comparisons between continental United States. In: Distribution, Biology, and Management of Exotic Fishes interspecific tilapia hybrids for some production traits. In: International Symposium on Tilapia (Courtenay Jr., W.R. and Stauffer Jr., J.R., eds.). The John Hopkins University Press, in Aquaculture (Fishelson, L. and Yaron, Z., eds.). Tel Aviv University, Tel Aviv, Israel. Baltimore, 322-373. Pp.559-569.

Terkatin-Shimony, A., Ilan, Z., Yaron, Z. and Johnson, D.W., 1980. Relationship between Whitehead, P. J. P., 1962. The relationship between Tilapia nigra (Günther) and T. mossambica temperature, ovarian recrudescence, and plasma cortisol level in Tilapia aurea (Cichlidae, Peters in the eastern rivers of Kenya. Proc. zool. Soc. Lond. 138 , 605-637. Teleostei) General and Comparative Endocrinology 40(2): 145-148.

Whitfield A.K. and Blaber S.J.M., 1979. The distribution of the freshwater cichlid Sarotherodon Trewevas E., 1983. Tilapiine Fishes of the genera Sarotherodon, Oreochromis and Danakilia . mossambicus in estuarine systems. Environmental Biology of Fishes 4(1): 77-81. British Museum (Natural History), London.

Wrigley T.J., Toerien D.F. and Gaigher I.G., 1988. Fish production in small oxidation ponds. Water Research 22(10): 1279-1285. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Created by A. Webb and M. Maughan © ACTFR, James Cook University, 2007 For further information please contact [email protected], tel: 07 4781 4262 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Other information sheets available:

Spotted tilapia – Tilapia mariae Guppy – Poecilia reticulates Oscar – Astronotus ocellatus Swordtail – Xiphophorus helleri Burton’s – Haplochromis burtoni Platy – Xiphophorus maculates

Mosquitofish – Gambusia holbrooki Three-spotted gourami – Thrichogaster trichopterus

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