The effect of feeds included some vegetable oil such as soybean, corn, sunflower and olive oil substitute of fish oil on the growth performance and body composition of sea bass (Dicentrarchus labrax) juvenile were investigated in this study. Fish oil is used as an oil source in the control group and soybean oil. sunflower oil. corn oil. and olive oil in the experimental groups respectively. Mean 12.33% oil was used in diets for all groups. At the beginning of feeding trials mean live weight of fish was found 7.58 g and this study was performed tor 75 days in a private hatchery in the town Oren, Mugla (Turkey). Growth performance of the fish was calculated by measuring live weight gain, specific growth rate, condition factor, hepatosomatic and viserosomatic index values. In addition, the amount of the nutrients in the fish and feed samples and total fat in the fish liver were determined. At the end of the study mean live weight gain offish were found 31.27 g in control group and 26.04 g. 24.79 g. 24.34 g. 25.76 g in the experimental groups I, II, II, IV respectively. Feed conversion ratio was found 1.59 in the control group and 1.75, 1.86, 1.94, 1.81 in the experimental group's respectively. The difference among the groups were found significant as a result of variance analyses for growth performance and body composition (P<0.05).
According to the results chemical analysis of total fat in the fish carcass were found 4.48% at the beginning and 4.55% in control group, 5.03%, 4.99%, 6.38%, 6.38%. in the experimental groups respectively at the end of feeding trials. Liver fat contents were found 13.84% at the beginning and 19.89%, 23.33%, 26.97%, 31.41% and 33.07% in the control and experimental groups I, II. II. IV respectively at the end of trial. Hepatosomatic index (HSI) values were found 2.06% at the initial and 2.10% in fish oil group, 2.42%, 2.45%, 2.31%, 2.43% in the other experimental groups at the end of trial. In similarly, viscerosomatic index (VSI) values were found 8.45% at the beginning and 9.24%, 10.19%, 11.51%, 11.70%, 11.94% in the control and the other experimental groups at the end of trial respectively. HSI and VSI values were found similar in the experimental groups fed the feeds included different vegetable oils and higher than the control group fed fish oil added feeds <P<0.05).