Marina Floating Thermometer with Suction Cup for Aquariums

By Marina
Rated 3.7483 out of 5 stars
$3.50Chewy Price
$4.48Chewy Price
In Stock
FREE 1-3 day delivery on first-time orders over $35

About This Item


  • Perfect for freshwater or saltwater use
  • Accurate and easy to read, provides readings in Centigrade and Fahrenheit
  • Safety zone indicator for most tropical fish
  • Helps protect your fish from unsafe temperatures
  • Designed to float in the water in a vertical position or includes an optional suction cup

See More


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Learn More About Marina From Our Team of Experts

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Fish TypeMarine Fish, Tropical FreshwaterBetta, Bottom Feeder, Cichlid...Betta, Cichlid, Goldfish...Tropical FreshwaterBetta
Aquarium TypeSaltwater, FreshwaterSaltwater, FreshwaterSaltwater, FreshwaterSaltwaterFreshwater

Questions & Answers

13 Customer Questions

What is the fluid inside this THERMOMETER? Just realize it broke! getting ready to drain tank freaking out my bala sharks might die. If anyone has any helpful advice about this thermostat please. It was in the back of tank was using as a back up incase digital went out. Sharks are Not eating today.
Answer by ChewyApr 19, 2018
The fluid inside the thermometer is a red dye mixed alcohol but the amount used should not be enough to cause harm to your fish.

Whats on the bottom of this?? And when should i replace this if i need to do so?
Answer by ChewyJan 11, 2019
In the very bottom of the thermometer, there is liquid alcohol and steel shot. If there is any damage to the thermometer, it should be disposed of, along with a water change and replacing the substrate, if pieces have broken apart into the aquarium.

Does is have mercury in it?
Answer by ChewyDec 07, 2017
This product doesn't have mercury.

How do I know what the temp is in the fish tank
Answer by ChewyNov 23, 2017
This product determines the temperature inside of your tank. As the temperature around the thermometer's bulb heats up, the liquid rises in the glass tube. When it is hot, the liquid inside the thermometer will expand and rise in the tube. The opposite happens when it is cold.

ReviewsWrite a Review

Rated 3.7483 out of 5 stars
151 Ratings
Would recommend to a friend

151 Customer Reviews

Rated 5 out of 5 stars
By Stacy on Nov 14, 2023

Accurate Thermometer

I needed a thermometer I could trust to give me accurate readings to keep my beta healthy and this seems to do that.

Rated 3 out of 5 stars
By kiminma on Jul 8, 2023


The temperature gauge seems to work, but even with my glasses, i can't see the temperature. I can see the green safe area, but can't tell what the temperature is.

Rated 5 out of 5 stars
By Turtletary on Nov 30, 2022

Right on temps!

Currently have an OLD Marina AQUARIUM thermometer - so wanted to get a new one to compare. They show exactly the SAME temps on either of the front corners! And of course they arrived with the other items in 2 days!!! Chewy always has what I need.. and in 2 days - regardless Holiday or Sunday.

Rated 1 out of 5 stars
By Debbie on Feb 6, 2023

Damaged goods

Got the thermometer but it is broken at the bottom

Rated 5 out of 5 stars
By ChihuahuaLover on Dec 11, 2022

Great Product and Value

Works exactly as described. I am going to buy another for my second aquarium.

Rated 1 out of 5 stars
By Ogre on Dec 15, 2022


Temp is off 5-10 degrees depending on water temp and difficult to read.

Rated 5 out of 5 stars
By Kola on Oct 17, 2022

Great thermometer

Much more accurate than the sticker ones but still cheap.

Rated 5 out of 5 stars
By Mowerman on Feb 26, 2022

Good for the Money

An inexpensive thermometer that works. Put the thermometer in my 55 gallon tank, and the thermometer gave an accurate reading based on my heater settings. The only problem is it's a little hard to read, though the Safe Zone, 70°F to 80°F, is well marked in red. I run my tank at 79°F, and the thermometer went right there and stayed. For the price what more could you want? I used the suction cup to hold my heater. This after having another, older floating thermometer in another tank, that always seems to drift to the back of the aquarium, or is turned away from the front. Looks good, works well, for a nice low price.

Rated 5 out of 5 stars
By Mace on May 13, 2022

perfect size easy to read

It’s a perfect size for my 3 gallon tank, easy to read. Love that it’s has the green lines to show where the temp should be!

Rated 1 out of 5 stars
By faunaVibrissae on Apr 9, 2022

Inaccurate and tiny

The reading is incorrect when compared with other thermometers and it's so tiny I can hardly read it even with my glasses.