Marina’s Floating Thermometer with Suction Cup for Aquariums is a reliable， high-quality floating thermometer. It’s accurate and easy to read and provides temperature readings in both Celsius and Fahrenheit. There’s also a clearly marked safety zone that shows the ideal temperature range for most tropical fish. The Marina Floating Thermometer works in both freshwater and saltwater tanks and is designed to float in a vertical position. A suction cup is included if you prefer to attach it to the aquarium wall.