SUMMARY:The cleaning efficiency of hosing wooden market fish boxes with cold water, the usual commercial practice, was very low, even when high pressure jets were used. After washing, the internal surfaces could still carry up to 20 × 106bacteria/cm2. Even prolonged steaming failed to sterilize the surfaces. Coryneform organisms accounted for over 50% of the total bacterial flora, although these have usually been reported as present in only low proportions on both fresh and spoiling fish. The major subsidiary groups were species ofAchromobacterandPseudomonas, constituting about 18% and 14% of the population respectively. A few micrococci and flavobacteria were also present.The conditions of counting, i.e. whether roll tubes or Petri dishes were used, whether incubation was at 0°, 20° or 37°, and whether the media were based on sea or tap water, could markedly influence both the magnitude of the count and the proportions of the different types of bacteria which could be isola