Abstract: An aquarium liquid security system is provided. The system includes an aquarium tank, i.e., a plurality of transparent material sheets joined at the sheet edges, and a liquid detection sensor. The sensor is at least partially wrapped around the perimeter, and is electrically responsive to liquid. An alarm interface is connected to the sensor. In one aspect, the sensor includes a pair of electrically conductive ink traces printed on the outside surfaces of the transparent material sheets. In another aspect, the sensor includes a liquid-permeable strip of material, a pair of electrically conductive traces, and a liquid-permeable adhesive attaching the sensor to the perimeter outside surface. Examples of liquid-permeable materials include cardboard, burlap, cotton cloth, synthetic cloth, paper, or cheesecloth. Alternately, the sensors can be formed on the interior surfaces of the aquarium and used for the detection of a low level of water.