Despite its high nutritional value, antioxidants are used in aquaculture products that have a short lifetime, as in other foods, to maintain quality during preservation. The purpose of this study; It is to observe the oxidative stability of sea bass (Dicentrarchus labrax) fillets at 0-4 degrees C using green tea extract obtained by classical brewing method, which is a method that can be applied by the consumer with ease. Determined concentrations (0.4-0.8-1.2 g / ml) and immersion times (10-20 min) green tea extract is applied and the fillets stored at 0-4 Thiobarbituric acid reagents (TBARs) analysis, sensory analysis and color analysis were performed on days 0, 3, 6 and 9 of storage. Depending on the literature, although no significant effect is expected, total aerobic mesophilic bacteria (TAMB) analysis was also performed additionally. As a result of the analyzes, significant differences were found when the TBARs results of all samples with green tea extract applied were compared with the results of the control group after 9 days of storage (p <0.05). At the end of storage, the 4th group (0.8% g / ml-20min) gave the best results with 0.31 +/- 0.009 mu mol MDA / g and there is a significant difference was found between the other groups (p <0.05). Green tea extract; As expected, it was determined that it did not have a significant antimicrobial and sensory effect. The color values caused a negative increase in the a * value, which expresses its green color as expected due to the color substances in its content, and a positive increase in the b * values, which express the yellow color. As a result of this study, it was found that green tea extract can be used as natural antioxidant in sea bass fillets.