With Aqueon, it's all about the fish. Aqueon makes a variety of aquarium solutions to sustain healthy and happy fish and aquatic life. Keep your tropical fish warm with the Aqueon Glass Adjustable Submersible Aquarium Heater. Constructed from thermal shatter-resistant, impact-absorbing quartz glass, this durable heater warms the water to between 68°F to 88°F. A power indicator LED light comes on during heating. For safety, the Aqueon Glass Adjustable Submersible Aquarium Heater is automatically turns itself off when not properly submersed to avoid overheating and damage.