The freshwater fish byproducts were stored under different conditions to obtain materials with different degree of freshness. Then Aspergillus oryzae koji was inoculated into byproducts to fish sauce fermentation at 35℃ for 30 days. The biochemical properties of fish sauce and byproducts were evaluated. The results indicated that changes in biochemical properties occurred during the storage of freshwater fish byproducts. The pH, total volatile base nitrogen (TVB-N), thiobarbituric acid (TBA) and total viable counts (TVC) in byproducts stored under the room temperature for 4hours were higher than that under ice and frozen storage, while the pH, TVB-N, TBA, and TVC content in byproducts under ice storage for 8hours were increased compared with byproducts under ice storage for 4hours. After fish sauce fermentation, the content of amino nitrogen and TSN in fish sauce made with byproducts stored under the room temperature for 4hours were the highest while the content of TVB-N and trimethylamine were also higher. The content of total biogenic amines and histamine were highest in fish sauce made from byproducts stored under temperature for 4hours. The byproducts did undergo biochemical changes under different storage conditions, however, there was no significant bad impact on the overall properties of fermented fish sauce. Thus, freshwater fish byproducts stored at the room temperature for less than 4hours was available for the fish sauce fermentation.