EVALUATION OF GROWTH  AND HETEROSIS OF JUVENILE OF NILE TILAPIA Oreochromis niloticus, BLUE TILAPIA Oreochromis aureus AND THEIR HYBRID REARED IN THE BRACKICH WATER POND  

Growth is one factor that was an indicator of success in aquaculture. Growth performance, especially  the character of weight, can be used as a determinant of the successfulnes of the selective breeding program through hybridization method. The hybrid between nile tilapia O. niloticus and blue tilapia O. aureus is expected to has better performances than their parents. This experiment aimed to observe the growth performance and the value of heterosis of the hybridization between nile tilapia and blue tilapia. The research was carried out for 6 months at the Research Institute for Fish Breeding at Sukamandi, West Java and brackish water pond at Cirebon (Indonesia). There were two strains or species of tilapia involved in this experiment, i.e. Nirwana strain of nile tilapia and blue tilapia. Inter and intra species of spawning were conducted communally in a freshwater pond sized of 25 m². Tilapia broodstock were stocked to spawning pond with male to female ratio of 10:30. After 14 days of stocking, larvae were collected then reared in the subsequent nursery hapas sized of 2x2 m for 60 days or after fingerlings reached the average individual length and weight of 4.82 cm and 2.20 g.

At the growing-up stage, fingerling were reared in the 3x5 m² net which was installed in the brackish water pond sized of 7000 m² at water salinity of 25-40 g/L  for 120 days. The stocking density applied at this stage 10 fingerling/m² strain population revealed the highest growth  performances with individual weight of 111.74 g, specific growth rate (SGR) of The fish were fed with floating commercial fish feed (30% crude protein) at a rate of 5-10% of biomass wich was given twice per day. The results showed that The crossing between female nile tilapia strains and male blue tilapia showed the highest growth performances and value of heterosis on the length, weight and survival characters (Table 1). It meant that the hybrids to have traits superior to those of either parent.