How can they retard fish spoilage?
White fish spoils for two quite different reasons. First of all, uncontrolled chemical changes take place after the fish dies through the action of special ferments called enzymes present throughout the tissues, which result in self-digestion of the flesh and a loss of substances that contribute to fresh flavours. Secondly, bacteria which are present on the skin and gills and in the gut of the living fish begin to increase in numbers after the fish dies, and break down the tissues. They produce stale flavours and finally the flesh becomes putrid. The rate of growth of the bacteria on the dead fish, already slowed down by the use of ice, can be retarded still further by application of antibiotics.
