The following fish samples were examined: control salted samples (A), salted samples with 0.1% of thyme oil (B), (salted samples with 0.3% of thyme oil (C), and salted samples with 0.5% of thyme oil (D).The study was based on microbiological (total viable count (TVC), Pseudomonas sp., lactic acid bacteria (LAB), Enterobacteriaceae, and H(2)S-producing bacteria), chemical (total volatile basic nitrogen (TVB-N) and thiobarbituric acid (TBA)), and sensory (colour, odour, taste, flavor, texture, and overall acceptance) analyses of changes occurring in the product as a function of treatment and storage time. The salted samples stored at 4 degrees C were taken as the control samples. Results showed that TVC exceeded 7 log cfu/g on day 12 of storage for control samples and day 21 for C and D samples. Populations of LAB, H(2)S-producing bacteria, Enterobacteriaceae, and Pseudomonas sp. reached higher final numbers in A and B samples than for C and D samples. Under B, C, and D treatments, TVBN values were lower than for A samples, whereas lipid oxidation, as judged by determination of TBA, did not occur during the refrigerated storage. Sensory scores of trout samples salted with thyme (groups B, C, D) decreased during storage time. However, at the end of the storage period, samples with thyme oil were acceptable by the panelist. The results of this study suggest that the shelf life in case of C and D samples was 21 d. The salting, thyme oil, and air packing were found to be effective, easy, and cheap methods of fish preservation.