An aquarium thermometer is a device used to read the temperature of the water inside your fish tank. It's important to know the water temperature, since fish have specific water temperature requirements to keep them healthy.
A tool that is used to measure temperature. As you have probably guessed by now, an aquarium thermometer allows you to accurately check the temperature inside your tank. This small device is an essential piece of aquarium equipment – if you own a fish tank, then you need an aquarium thermometer.