An eco aquarium structure of this invention comprises a water pumping motor in the water connected to a bottom sand filter. A water drainage pipe facing outside is defined at the outer edge of the left side of the bottom of the aquarium. The water drainage pipe is connected to a soft pipe to drain the dirty water in the aquarium. A water drainage valve is mounted at the outer edge of the left side of the bottom of the aquarium and connected to the water drainage pipe at the left side and the bottom sand filter board at the right side. The water drainage valve is a spherical rubber plug which is connected to an iron bar. The water may be drained away when the iron bar is lifted, and the water drainage may be terminated by inserting the spherical rubber plug. Multiple blocking bars are mounted inside and around the aquarium of this invention. A V-shaped transparent partition plate is mounted on each blocking bar. The concaved slot at the bottom of the V-shaped transparent partition plate is hollow, and the convex rib at the top of the V-shaped transparent partition plate has no holes. Little shrimps and daphnia may be raised under the hollow concaved slot at the bottom of the V-shaped transparent partition plate. To address the habitual behavior of daphnia which float up to the water surface, the V-shaped transparent partition plate can prevent daphnia from unlimitedly floating up to the water surface because there is no hole at the top of the V-shaped transparent partition plate, and thus daphnia are not eaten by fishes. Because of the V-shaped transparent partition plate, the food fed into the aquarium is eaten by the fishes first, and then by shrimps, and eventually by daphnia. Therefore, the food is used efficiently and thus can prevent pollution of the water in the aquarium by the residual food. The fish stool falling down can be used as the nutrients for algae and bacteria at the bottom layer of the aquarium. The algae and bacteria are the food of daphnia, the n
