Fillets from rainbow trout fed astaxanthin or canthaxanthin were packaged under air and modified atmosphere, 60% N 2 /40% CO 2 and 60% Ar/40% CO 2 , and stored at +2°C for 26 days. Fish samples were analyzed at day 0, 5, 9, 13, 16, 19, 22, and 26 after processing. Drip loss, internal pH, surface color, carotenoid content, total lipid content, thiobarbituric acid reactive substances, and microbial contents of fish fillets were determined. A significant positive effect was found between pigment fed, gas used, and time of storage for the analyzed parameters. The use of argon Georges Choubert, PhD, and Frédéric Brisbarre, MSc, are affiliated with