best heaters available for your betta tank. It features an adjustable heating setting that ranges from 68-88 degrees that provide the ideal temperature of 78 degrees for Bettas, right in the middle. This heater is highly durable and shatterproof as well. It features an LED light that is red during heating and green when the desired temperature has been achieved. You don’t need to worry about tank overheating as it automatically turns off when it is at the set temperature. It is a fully submersible heater that consists of an electronic thermostat for an accurate temperature setting. Moreover, it can be used for both saltwater and freshwater tanks. This heater can be positioned both horizontally and vertically. Its only disadvantage is that initially, it takes a little while to heat the tank.
ViaAqua 50-Watt Quartz Glass Submersible Heater

ViaAqua 50-Watt Quartz Glass Submersible Heater is high quality and one of the best-selling heater that includes a fully adjustable temperature and a clear display that helps you make easy adjustments. The quartz glass construction makes it durable and high quality. It comes with suction cups which makes it easy to install. At 8.2 inches length, this heater is fit for a tank size of up to 13 gallons. It comes with a built-in thermostat that allows a temperature range of 68-93 degrees. This heater does a great job of maintaining a consistent temperature. But it may require a separate thermometer as the thermostat is not the most accurate.