Thermal properties of Brain, gill, hepatopancreas, muscle and blood of Carassius living in 8°C were investigated by differential scanning calorimeter. Between 20°C～-40°C , blood showed lower specific heat capacity than other organs. It might help temperature equilibrium in organism. Blood and brain had higher freezing temperature. Brain showed the maximum water content but less freeze water while ventral muscle had the lowest water content but high freeze-able water. Hepatopancreas had both low water and freeze-able water content.