Abstract: A fish guard includes a panel, a plurality of columns of apertures, and a hooked shape top section operatively attached to the panel and configured to detachably engage a top edge of a wall of an aquarium receptacle. Each column of apertures includes a plurality of apertures disposed in substantial horizontal alignment. Each of the plurality of columns of apertures is also substantially in vertical alignment and horizontal alignment with a vertically disposed slot of the receptacle when the fish guard is installed. A kit includes a front fish guard and two side fish guards.