$54.99 300/500W Titanium Aquarium Heater For Fish Tank with Indicator Light Temperature Adjustable 
Amazon.com : Hydor 7.5w Slim Heater for Bettas and Bowls, 2 to 5 gal : Aquarium Heaters : Pet 
Aquarium Heater 50W Anti-Explosion for Tropical Fish Tank 10 to 16 Gallon Aquaneat - Walmart.com 
