Dynamics of Oreochromis niloticus niloticus (Tilapia, Cichlidae) in an arid medium in Algeria A. ARAB, & I. HARRACHE.

University of Sciences and Technology Houari Boumediene, Biological Faculty of Science, LP 39, El Alia, Algiers, Algeria.E-mail: [email protected]

Algeria has, of share its situation geographical, its relief and its sites natural or artificial, a rich and favourable ecological medium for the development and the increase in the aquacole production and the breeding of fresh water fish. The first work on the ichtyofaune shows again at the beginning of the 20th century, on the three families Cyprinidae, Clupeidae and Anguillidae, but currently there are other families like: Centrarchidae, Percidae, Mugilidae, Cichlidae, Esocidae, Sparidae and Siluriformidae, with 25 fresh water fish species. The aquiculture produced 250 tons in 1999 including 76,9% of fish of fresh water (repopulation of stoppings by carps and sandres) and 476 tons in 2002 made up to 85% of production of fresh water. The consumption of fish is estimated at 4,62 kg/hab/an. The first introductions of Tilapia zili, Tilapia mossambica and Tilapia rendalli coming from France go back to 1960, in Oued Righ (W. EL WADI), Tolga (W. BISKRA) and Ain Skhouna (W. SAIDA). It is only in May 2002, that there was the importation of Egypt especially in the private exploitations of 3700 alvine and 200 parents of Oreochromis niloticus niloticus and 12400 alvine in 2003, 4000 in 2004 and as much in 2005. In 2004 the first introduction took place in the aquacole farm Rouani located to (Hassi lefhal W. of Ghardaïa) at 800 km to the south of Algiers, where 1000 alvine and 100 parents of Oreochromis niloticus niloticus were imported of Egypt. In basins of reproduction are placed, 3 females for a male. Each female can give up to 300 alvine which is installed in basins at a rate of 1000 alvine for 1 m². The food is composed of 40% from corn, 30% of but, 20% of soya, 5% of CNV and 5% of amino acids. Tilapia (10000 individuals) are high in basins of 100 m² and 350 m² respectively for the classes of sizes of 100 G and 300 G the first class of size is obtained after 75 days of enlargement and 4 months for the second class of size. When the conditions are favorable (Temperature higher than 22 °C, good oxygenation and a sufficient and controlled food) the tilapias can reproduce every 21 days.

Key words: Pisciculture, Tilapia, arid climate, Algeria