AquaTop’s PISCES Nano Aquarium Heaters. The compact design allows for versatile placement in small aquariums such as our PISCES All-in-One Aquariums. Each unit has a built-in electronic thermostat preset to 78? F for precise temperature-controlled accuracy of 1.8? F. When the target temperature of the heater has been achieved, the unit will shut down and stop heating the water. Constructed from a heat-resistant quartz material, the PISCES Nano Heaters will heat your aquarium water quickly and accurately, plus the included suction cups allow quick and easy installation. May the PISCES Nano Heaters help keep your aquatic creatures warm!