The relations of relative humidity (R.H.) to water content in precooked, air-dehydrated fish were determined with reference to the mould, bacterial and volatile-base content of stored samples. In general it was found that visible mould developed only in samples stored at 80% or higher R.H., while bacteria increased only at 85% or higher R.H. Viable bacteria and moulds decreased slowly in samples stored at R.H. too low to support their active multiplication. Total volatile bases and trimethylamine increased in samples stored at R. H. too low for growth of either bacteria or moulds.