Aquarium Glass Water Thermometer Easy to read and Accurate Readings on a Celsius scale Self Adhesive Sucker Glass aquarium thermometers can display a temperature range from 0C-50C in a reliable. Perfect for beginner aquarist on a budget! It is always advised to monitor your fish tank and ambient air temperatures to ensure you are providing a perfectly controlled environment. Keep it old school with a glass thermometer, cheap and foolproof!