Frozen fillets from cod which had been starved in an aquarium developed less cold store flavour or odour at −10°C than was developed by fed controls. Cis-4-heptenal, the major compound responsible for the off-flavour, was found to be present at a much lower level in the starved fish. At the same time the relative proportions of phospholipids and of the most important polyunsaturated fatty acids were found to be reduced by starvation. It was concluded that selective mobilization of precursors reduced the formation of the flavour compound during subsequent frozen storage. A seasonal variation in cold store flavour (and odour) therefore seems almost inevitable.