The Biology and Culture of Tilapias

several systems by which earthen ponds can be manipulated to produce and
remove hybrid fingerlings and fry.
Lovshin (1980) describes a series of experiments performed in Brazil
to determine the best method for producing all-male tilapia hybrid fingerlings
by crossing S. niloticus x S. hornorum. One hundred and forty-two crosses
were made over a 6-year period in 360-m2 earthern ponds. A fingerling
production system for use in Brazil was developed from these experiments
and is detailed below (Figure 1). Plates 1-3 (see p. 308) illustrate some of the
facilities and species in use in Brazil.

Sarotherodon

hornorum

Step I

Pure Genetic

Id Strains

Sarotherodon

niloticus

I

Step n

I

Broodstock

Multiplication Ponds

males are sexed

at 20 to 30 grams

females are sexed

at 20 to 30 grams

Step IU

Male and Female

Preparation Ponds

\

Step ISZ

$s. hornorum

Q S. niloticus

Spawning Pond

Stocked at 60 to 100 grams

Figure 1. System used for producing all-male tilapia hybrids, S. niloticus x S. hornorum

in Northeast Brazil (after Lovshin 1980).