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Desirable attributes of
Species used in small scale Alien species in African aquaculture |
Oreochromis macrochir (Greenhead tilapia)
Family: Cichlidae Size: Maximum approximately 30-32 cm. Males larger than females. record 1.86 kg. Native range: Cunene, Okavango, upper Zambezi, Kafue, Lake Kariba and Busi. Habitat preference & tolerance levels: Prefers quiet deep waters along river margins but found in other habitats including floodplains and impoundments. Appears to prefer riverine to lake environments. Juveniles found close inshore in shallow water in vegetated localities. In native range occurs at temperatures from 18 - 35°C but can tolerate temperatures as low as 11°C in certain situations. Generally has a high tolerance to low DO levels, but juveniles more tolerant than adults and remain in spawning grounds up to a length of 180 - 200 mm. Although this species can tolerate moderately high salinities, it is not as tolerant as some other cichlid species. Will not tolerate salinities > 20 ppt. General biology and aquaculture potential: Feeds on microscopic material - algae (especially diatoms) and detritus. Juveniles consume zooplankton and insect lavae. Breeds in summer. Males construct nest in shallow water, several nests often in an arena. Females mouthbrood eggs, larvae and small fry. Juveniles remain in small school near parent for few days, re-entering female's mouth during times of danger. Juveniles become independent after 21 days at TL of 13 - 15mm. Breeds several times during the summer period from October - March. In warm waters can produce up to 8 spawnings per year at intervals of 6-7 weeks. Females of 160 - 270 mm SL produce 1000 - 1500 eggs. Often used in polyculture together with O. andersonii and T. rendalli. Growth: Under optimum pond conditions males may reach almost 0.5 kg. in one year. Females achieve 2/3 of this weight. Most individuals will not spawn until they reach 20-22 cm. Breeding may occur as early as 8 months in optimal warm conditions. In other regions spawning starts during the second year. Lì: 241.6 - 394.8 k: 0.425 - 0.312 to: between - 0.930 and - 0.276 Regions farmed: References: Bruton 1979e, Chapman et al 1971; Dudley 1974, 1979; Kapetsky 1974; Mortimer 1960; Philippart & Ruwet 1982; Skelton 1993; Trewavas 1983; |
