are mainly known as freshwater fish that inhibiting ponds, lakes and river but
some of it species live in brackish water due to their tolerance to high
salinity. Some country claimed this species as invasive species such as
Australia but farmed extensively by many countries in Asia region such as
Malaysia. Farmed tilapia production is about 1,500,000 tones (1,500,000 long
tons; 1,700,000 short tons) annually with an estimated value of US$1.8 billion
(De Silva, 2004), about equal to that of salmon and trout.
Thus, many fish farmers attempt to make
different technique in breeding to increase their production in aquaculture
practices and one of the technique is crossbreeding. Crossbreeding is the
mating of individuals of different species, varieties or lines to find new
species or varieties that have potential to be introduce. This process combines
the best of each individual breed and its genes into a more heterozygous animal
(Burnside, 2004). Hybrids show characteristics of both parents and when a
hybrid shows characteristics superior to both parents, it is said to have
hybrid vigour or positive heterosis, which is the goal of breeding (Masser,
1998). Moreover, crossbreeding also has been used to produce hybrids that have
improved growth rates, survival rates, lower food conversion rates, improved
disease resistance, etc. (Tave, 2003).
Common Red tilapia (Oreochromis spp.) grow rapidly on formulated feeds with lower
protein levels and tolerate higher carbohydrate levels than many carnivorous
farmed species. They can also accept feeds with a higher percentage of plant
proteins. It is easy to breed tilapia and culture them intensively and
economically. They are relatively resistant to poor water quality and disease.
Their hardiness and adaptability to a wide range of culture systems has led to
the commercialization of tilapia production in more than 100 countries. Their
widespread consumer appeal will fuel the expansion of the tilapia industry for
years to come.
Black tilapia (Oreochromis mossambicus) are hardy and can easily establish in
natural waters (GISD ,2006). This species also known for their high tolerance
toward water salinity and but poor in breeding performance. The major
constraint of Oreochromis niloticus
is related to its commercial value and easy production, while Oreochromis mossambicus with its hardy
and high salinity.