Three different species of fish (sea trout, Spanish mackerel and catfish) were studied. Samples undergoing normal spoilage were compared with samples which had undergone a sanitizing treatment with alcohol. Differential temperature storage studies were conducted at 290 °F (-1.7 °C) and 32 °F (0 °C). Fish quality was assessed by means of microbiological, chemical and sensory analyses. Quality assessment via measurement of proteolytic and lipolytic enzymes was attempted, but these enzyme activities were not detected in any of the samples. It was not possible to differentiate between the contributions of microbial and autolytic spoilage. Alcohol treated samples (reduced numbers of microorganisms) had shelf-lives extended by 6-10 days over untreated samples. The shelf-life of samples stored at 290 °F was extended by 6-10 days over the shelf-life of samples stored at 32 °F. Treated samples stored at 290 °F received highest sensory scores and untreated samples stored at 320 °F received the lowest scores. It was seen that the three fish species studied had different shelf-lives: sea trout-6 days, Spanish mackerel - 10 days and catfish - 16 days. Decomposition rates differed significantly between species and this factor must be taken into account when marketing strategies are developed by firms engaged in fresh fish sales. / Master of Science