Effects of Salinity on the Feeding Efficiencies, Growth Performances and Survival Rate of 11th Strain of Tilapia (GIFU) in Laboratory Condition

摘要

Feeding experiment was conducted for 45 days to evaluate the effects of salinity on the feeding efficiencies, growth performances and survival rate of 11~(th) strain of tilapia, Oreochromis niloticus (GIFU) in laboratory condition. Three rectangular glass tanks were used for the experiment with different level of salinity (0 as control; 8ppt and 10ppt (ppt means parts per thousand, g/l) as treatment 1 and treatment 2 respectively) using two replicates for each level of salinity. Seventy-five fingerlings were stocked in the tanks. The investigation was conducted at one feeding rate (3% of body weight) which has given twice a day in a 1 X 2 factorial experiment. Average food conversion ratios (FCR) were 2.66 ± 0.04, 1.76 ± 0.04 and 1.69 ± 0.07 in controls, T_(1), and T_(2) respectively. Average protein efficiency ratios (PER) were 0.63 ± 0.04, 1.31 ± 0.01 and 1.68 ± 0.02 in control, T_(1), and T_(2) respectively. The feed efficiency (FE) were 35.22 ± 1.54, 32.45 ± 1.22, and 31.54 ± 1.85 in control, T_(1) and T_(2) and specific growth rate (SGR) were 0.42 ± 0.03 %/d in control, 0.99 ± 0.03 %/d in T_(1 )and 1.34 ± 0.09 %/d in T_(2 )respectively. The net weight gain of fish in T_(2 )(39.12 ± 0.17 g) and T_(1) (31.1 ± 0.02 g) were significantly higher than that of control (30.00 ± 0.21 g). The net length gain of fish in T_(2 )(12.12 ± 0.03 cm) and T_(1) (10.5 ± 0.02 cm) were significantly higher than that of control (9.5 ± 0.04 cm). The survival rates were 85%, 100% and 100% in C, T_(1) and T_(2) respectively. The proximate composition of fishes, water quality parameter, feeding efficiencies and growth performances were better in T_(2 )than that of T_(1) and C. The best growth was found from T_(2 )(salinity 10 ppt) and lower growth was found from control (salinity 0 ppt) in case of GIFU. The present study revealed that GIFU can tolerate a wide range of salinity and shown better growth and survival rate.