One of the main concerns in the production and processing of fishery products is the issue of storage and increasing its shelf life. In this regard, this study aims to investigate the effect of chitosan-chia seed gum coating (2% and 1.5% of the sample weight, respectively) on some chemical properties (the amount of free fatty acids, peroxide, thiobarbituric acid index, volatile nitrogenous bases and pH). , microbial (number of Escherichia coli bacteria) and sensory of phytophagous fish during storage period (0, 3, 6, 9 and 12 days) was done at refrigerator temperature. The results showed that the amount of free fatty acids, peroxide, thiobarbituric index, volatile nitrogenous bases and the number of Escherichia coli bacteria in all the samples increased with the increase in storage time, and this increase was less intense in the samples coated with chitosan-chia seed gum solution. The findings indicated that with increasing storage time, the pH level increased in the uncoated samples, but in the coated samples, the pH level decreased at first and then increased. The sensory evaluation of the samples also revealed that the overall acceptance of the samples decreased with the increase in storage time and after the third day of storage, the coated samples received more points than the uncoated samples from the evaluators. Finally, this study showed that the use of chitosan-chia seed gum coating can help increase the shelf life of fish fillets in the refrigerator.