Carbon monoxide (CO) has been applied to fish muscle for colour stability and consumer preference during frozen storage and transportation. This study compared the changes in aerobic plate counts (APC), pH, total volatile basic nitrogen (TVB-N), K-value, colour, and sensory analyses between CO-treated and untreated tilapia fillets stored in ice and refrigerated at 5°C up to 14 days. Except for Hunter a* value, the two test fillet groups resembled each other in the freshness quality profiles during storage although the initial levels of APC, pH, and K-value varied slightly. The CO-treated fillets had significantly higher a* values and higher freshness grading scores than that of the untreated fillets. Good correlationships among K-value, overall, colour and odour qualities were demonstrated. The shelf life was 8-9 days and 4-5 days stored in ice and refrigerated temperatures, respectively on the basis of sensory characteristics and K-values. The consumers surveyed in this study had a preference for tilapia fillets with enhanced red muscle color; however, it did not bias acceptability.