الفهرس 
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Abstract
A 8-month (from April 1st to December 1st 2013) study was carried out at two private commercial farms {two (systems) x four (ponds) x 8000 (m2) with water column 1.6 m in depth} which locates in the second depression of Wadi El-Rayan, Western Desert of Egypt, Fayoum governorate, Egypt. This study was conducted to compare the effects of feeding form (sinking and floating) commercial pellets (27% crude protein) on the performance of mono-sex Nile tilapia Oreochromis niloticus fry (mean weight of 0.3 g/fish) reared under extensive and semi-intensive systems. The experimental design which has 4 treatments (T1; T2; T3 and T4 with 2 replicates per each) 2 (diet forms) x 2 (system). Under the extensive and semi-intensive system, 12& 24 thousand O. niloticus fry were stocked in every pond, respectively. All ponds were fertilized by only one dose of inorganic fertilizer (50 kg super-phosphate/feddan) before landing the fry, after two weeks the fry was landing in ponds after that ponds were fertilized by chicken manure biweekly at a rate of 2 m3/feddan during the first two month, then the fish are fed on sinking and floating commercial pellets at a rate of 5% fish biomass daily except Friday for 8 month. Some physio-chemical parameters; chlorophyll “a”, zooplankton assessments and some growth performance parameters of the fish were determined biweekly. Finally an economic evaluation was studied.
The results showed that the optimum growth performance, total production and economic evaluation were obtained at semi-intensive culture with floating feed of mono-sex Nile tilapia niloticus in earthen ponds. Therefore, it could be recommended for applying and extending out these results under Egyption conditions.