الفهرس 
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Abstract
World fisheries have reached their maximum potential, and their production has leveled off during the past decade (FAO, 2014), while the demand of aquatic food is increasing (FAO, 2006). Consequently, aquaculture, which is the farming of aquatic organisms including fish, mollusks, crustaceans and aquatic plants (FAO, 2006), has become one of the main sources of fish for human consumption.
Global aquaculture production has been increasing at an outstanding rate during the past two decades. As a result, global aquaculture production has jumped from 41,724,624 tons in 2000, representing only 30.6% of fish total production to reach 90,432,105 62 tons in 2012, representing 49.46% (FAO, 2014).
1.1. Aquaculture in Egypt
Aquaculture has been known in Egypt since the beginning of written history. Tomb friezes dated back to 2500 B.C. illustrated the harvest of tilapia from ponds (Bardach et al., 1972). A traditional form of aquaculture had been known as “hosha” and has been practiced in Egypt for many centuries (Eisawy and El-Bolok, 1975) until a few decades ago in the Northern Delta Lakes region (FAO, 2005). Modern aquaculture began in Egypt in mid 1930s (FAO, 2005). However, aquaculture industry has witness a substantial expansion during the past decades. As a result, Egyptian aquaculture production increased rapidly from 340,093 tons in 2000, representing 46.95% of total fish production to 1,017,738 tons in 2012 representing 74.2% of total production (1,371,976 tons) (GAFRD, 2014).
Aquaculture in Egypt is practiced mainly by private sector, which contributed about 99% of total aquaculture production (976,728 tons) in 2011. Semi-intensive culture in earthen ponds is by far the most important farming system in Egypt. Semi-intensive fish culture is practiced mainly in brackish water environment, particularly around the northern delta lagoons. Semi-intensive production in earthen ponds has sharply increased from 191,000 tons in 1999 to reach 734,891 tons in 2011, representing 74% of total aquaculture production (986,820 tons) (GAFRD, 2012).
1.2. Tilapia culture
Tilapias are currently the second largest farmed finfish group in the world, only after carps (FAO, 2014). They have many attributes that make them excellent candidates for aquaculture. These include their fast growth rates, high tolerance to a wide range of environmental conditions, resistance to stress and disease, the ability to reproduce in captivity, the ability to feed at a low trophic level, and the acceptance of artificial feeds immediately after yolk-sac absorption (El-Sayed, 2006). As a result, tilapia culture has
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witnessed substantial global expansion during the past two decades. Consequently, the global production of farmed tilapia has increased from 383,654 tonnes in 1990, representing 4.5% of total farmed fish production, to 4,507,002 tonnes in 2012, representing 10.2% of total farmed fish production (FAO, 2014), with an average annual growth of 13.5%.
Figure 1. Fish production in Egypt during 1960-2011 (FAO, 2012 and GAFRD, 2012).
1.3. Tilapia culture in Egypt
Tilapia culture has traditionally been practiced in Egypt for thousands of years. An Egyptian tomb frieze dating from about 2500 B.C. depicts a tilapia harvest and suggests that fish may have been cultured for human consumption (Chimits, 1957; Bardach, Ryther and McLarney, 1972). However, the first modern commercial tilapia farm was built in 1957 at Manzala (near Mansoura, Dakahlia governorate) and operated by the Egyptian government.
Tilapia culture in Egypt has been expanding at a sharp rate during the past two decades. Consequently, the production of farmed tilapia has increased from 157425 tons in 2000 representing 46.29% of total aquaculture production to 768,752 tons in 2012, contributing 75.46% to total aquaculture production (GAFRD, 2014). Therefore, Egypt is currently the second-most tilapia producer in the world, after China (FAO, 2012.