The Biology and Culture of Tilapias

First Year

Pure Genetic Strains

spawn in laboratory

I

growth in laboratory

or ponds up to 50 grams

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Sarotherodon aureus

sexing and elimination

of females

I

overwinter

Sarotherodon niloticus

spawn in laboratory

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1 I

growth in laboratory

or ponds up to 50 grams

I

sexing and elimination

of males

I

overwinter

Second Year

1 ~arotherodon aureus d 1 1 ~arotherodon niloticus^9
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hybridization

growth of hybrids in

nursery pond up to 50 grams

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sexing of male hybrids

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overwinter

Third Year

production

Figure 2. System used for producing tilapia hybrids, Sarotherodon niloticus x S. aureus in
Israel (after Morissens 1977).

50 g, the fish are sexed and only the female S. niloticus and male S. aureus
are kept. Often the female S. niloticus and male S. aureus are tagged so that
they can be identified from wild, unselected tilapia. Selected female S.
niloticus and male S. aureus broodstock are overwintered in deep earthen
ponds, small ponds or concrete tanks covered with polyethylene sheets or
supplied with heated water. In the spring the selected broodstock are stocked
into earthern ponds of approximately 1 ha with a water depth of about
50 cm. The stocking density is 150 to 200 S. aureus males with 500 S.
niloticus femaleslha. Mires (pers. comm.) reports that the fish farming
kibbutz where he works has doubled hybrid fingerling production by in-
creasing the number of females stocked to 1,00O/ha and altering the ratio
of females to males to 1: 1.