Thermometers
Aquarium thermometers: a glass thermometer, digital thermometers and a Bluetooth thermometer to watch the water temperature.
How to choose?
Advice and care
How to choose an aquarium thermometer
A thermometer shows at once whether the heater is doing its job.
Readability
A digital thermometer is easy to read even from a distance.
Placement
Fit it in good flow, away from the heater, so the reading holds for the whole tank.
On your phone
A Bluetooth thermometer lets you check the reading on your phone.
Frequently asked questions
What temperature suits tropical fish?
Most tropical aquarium fish do well at 24–26 °C. Check what your species need.
Why do the thermometer and the heater show different temperatures?
A heater's dial is approximate and the water next to it is warmer. Trust the thermometer and set the heater by it.
Read more
Fish are cold-blooded: their metabolism, appetite and resistance to disease depend on the water temperature. Even a few degrees off stresses fish, and a faulty heater can overheat the water or let it cool down. A thermometer is the simplest way to notice this before the fish fall ill.
The range includes a classic glass thermometer that attaches inside the tank with a suction cup, digital thermometers with a clear display, and a Bluetooth thermometer whose reading you can check on your phone. A glass thermometer needs no battery, while a digital one is easier to read.
Check the temperature every day at the same time, for example when feeding. Do not place the thermometer next to the heater or right under the light, as it will then read too high. In summer a thermometer also helps you notice overheating when the room is hot.