Conductivity is regard as a key technical parameter in modern intensive fish farming management. The water conductivity sensors are sophisticated devices used in the aquaculture monitoring field to understand the effects of climate changes on fish ponds. In this paper a new four-electrode smart sensor is proposed for water conductivity measurements of aquaculture monitoring.The main advantages of these sensors include a high precision, a good stability and an intrinsic capability to minimize errors caused by polarization. A temperature sensor is also included in the system to measure the water temperature and, thus, compensate the water-conductivity temperature dependence. The prototype developed is appropriate for conductivity measurement in the range of 0-50mS/cm, 0-40 ℃. A cure relationship was found between the out-put value of each standard solution measured by the sensor and the electric conductivity concentration.