The growth/survival of Aeromonas spp. and Yersinia enterocolitica on cod and trout stored in two modified atmospheres at 0 degrees, 5 degrees and 12 degrees C was compared with that on aerobically stored fish. Both organisms grew on aerobically stored fish at all three temperatures. Growth on the modified-atmosphere-stored fish was never greater and was generally markedly less than on aerobically stored fish. This reduction in growth was greater in the higher carbon dioxide-containing atmosphere and at the lower temperature(s).