Aquarium_heater
An aquarium heater is a device used in the fishkeeping hobby to warm the temperature of water in aquariums.[1] Most tropical freshwater and marine aquariums are maintained at temperatures that range from 22 to 30 °C (71-86 °F).[1][2][3] The types include glass immersion heaters and undergravel heating. There are also heating mats that may be placed under the aquarium.[4]