An aquaponic system includes a frame, an aquarium located at a lower portion of the frame and provided with a motor, a plurality of cultivating tanks arranged on the frame and having two opposite sides provided with a plurality of inlet tanks and a plurality of outlet tanks, and a strainer unit mounted on the frame. Each of the outlet tanks is connected with a lower one of the inlet tanks. The strainer unit includes a water outlet port connected with the water inlet pipe, a water inlet port connected with a water feeding pipe, two hollow clamping plates located between the water outlet port and the water inlet port, a filtering sponge clamped between the two clamping plates, a fertilizer ferment chamber located under the water inlet port, and a drain pipe connected with the fertilizer ferment chamber.
