Fifteen species of microorganisms were isolate form the intestines of fishes, fish feed, and ferment. Eleven microorganisms except HY4, HY8, HY12, and HY13 were Gram-positive, and HY1, HY2, HY3, HY5, HY6, and HY7 produced lactic acid. The species of HY1, HY2, HY3, HY4, HY5, HY6, HY13, and HY14 showed some growth in the medium containing 1% of NaCl. Except HY6, HY7, HY8, HY12 and HY5, 10 isolates had proteolytic activity, whereas only HY13 and HY14 had lipase activity. From all the results four isolates (HY3, HY4, HY13 and HY14) were chosen for the degradation of fish wastes. There was no mutual inhibition among the microorganisms, and the optimum temperature and pH for the growth of the mixed culture were found to be 3 2$^{C}$ and 7, respectively. Under the optimum growth conditions the maximum optical density and the maximum specific growth rate were estimated to be 2.35 and {TEX}$0.46h^{-1}${/TEX}, respectively. Major microorganisms in the mixed culture at the log-phase were HY3 and HY4, which occupied 70%. The degrading efficiency of fish waste by the mixed microorganisms was 2.3 times higher, compared to control. The total amount of free amino acids in the degraded products from fish wastes was 39g/100g protein and little odor was produced by the mixed microorganisms after 48 hours.