Abstract: A novel aquarium assembly includes a transparent fish tank that is made of integrally molded plastic. The fish tank confines large and small receiving spaces therein. A top cover is mounted removably on the open top of the fish tank and is formed with an opening to access the large receiving space. A U-shaped filter strip is disposed inside the small receiving space and divides the small receiving space into a first compartment and two second compartments on two sides of the first compartment. The second compartments are communicated directly with the large receiving space.