Effect of Different Levels of Feeding During Acclimatization in High Salinities on Gonadosomatic Index And Survival Rate of Adult Red Hybrid Tilapia, Oreochromis sp.

A 15 day acclimation experiment was conducted to determine the optimum feeding level during an acclimatization period to marine water for improving survival rate and gonadosomatic index (GSI) of adult red hybrid tilapia in high salinities. This experiment examined four levels of feeding as the follows; treatment (T1) the control group, which was acclimated without feeding, T2, T3 and T4 were fed at feeding rates 0.5, 1, and 2% of brood-fish weight, respectively. Using mixed sex stocks of adult red tilapia, fish were randomly stocked at rate of one fish / 10 liters in 8 plastic tanks (60 liters) with an average initial weight of 48.75g. Mediterranean Sea water was used to gradually raise the salinity. The statistical analyses appeared significant differences among treatments and confirmed that the growth and GSI indicators are affected by different feeding levels. 0.5% (T2) and 1% (T1) as feeding rates for adult red hybrid tilapia during the acclimatization period had the best and highest in theses indicators in comparison with the control treatment and T4.