Even though goldfish are adaptable creatures and can do quite well in cooler water, they grow fastest and display the most optimal health in constant warm temperatures.
Finding a reliable brand of aquarium heaters is difficult. The first thing I want to know is “can you set the temperature yourself?” Many come pre-dialed. This heater allows you to set the temperature precisely ranging from 68-93 degrees F. Simply turn the little red nob on top. Secondly, is it reliable? Will it burn out within a few weeks, or worse yet experience a short that fries your precious fish? This can and does happen with some brands, but thankfully in my experience not with Aquatop. The heater is double-insulated and can be fully submerged under water, though I don’t recommend doing that with any brand (this one included). This aquarium heater is 300-watts rated for up to 75 gallons.