Aqueon offers an assortment of heaters that provide the warmth essential to tropical fish’s survival and overall wellbeing. Heaters are built with different wattages, so it is imperative choose a heater that best fits the aquarium size. Review a heater wattage and aquarium size comparison chart to ensure the appropriate heater is installed inside the aquarium. It is also suggested to do research on the type of fish inside the aquarium so that the water temperature is maintained at a level that the fish breed thrives.