An aquarium heater helps to keep your fish tank temperature in order to provide the most comfortable environment for your tropical or freshwater set up. An aquarium heater is needed to heat the water to the temperature that allows your aquatic life to thrive. As fish are unable to produce body heat, a fish tank heater is an absolute necessity for pet fish to maintain healthy immune systems. An aquarist's goal is to replicate the natural aquatic habitat for pet fish and other aquatic life to keep them healthy and stress-free. In selecting from the assortment of submersible aquarium heaters and other various types of heaters available, it's important to keep in mind that the size of your tank plays a key role as smaller tanks may require smaller aquarium heaters. Additionally, the species you are caring for plays a key role as many fish indigenous to the warmer waters of the tropics typically need to swim within those same temperatures in order to survive. To promote the health and longevity of your aquatic life, you will need to select the correct fish tank heater for your freshwater or marine set up.Keep your aquarium beautiful while maintaining the correct temperature for your school. Many submersible aquarium heaters have been cleverly designed to be unnoticeable once mounted, and they are available in a range of wattages to accommodate almost any size aquarium. For your convenience, there are even fish tank heaters that are equipped with an electronic thermostat and a power monitor light. Most aquarium heaters have been constructed to be shatter resistant for ultimate durability. Some are equipped with a safety mechanism that automatically shuts off the heater to prevent overheating. Other aquarium heaters, meant for use with tropical fish, need no adjustment as they are programmed to maintain a constant water temperature of 78ºF. From mini aquarium heaters to submersible aquarium heaters, Petco offers a variety of options to keep your tank at proper temperatures all year long.