Best Aquarium Thermometers 2023 – Buyer’s Guide & Reviews

The temperature of aquarium water has one of the most important values when you keep fish in an aquarium. If you want to keep more fish, you will have to conduct more careful monitoring of the water temperature. To measure the water temperature in the aquarium, special thermometers are used. Modern heaters for aquariums are often equipped with sensors for temperature control, but these sensors often have large errors, so the use of an aquarium thermometer is most preferable. For this purpose, we have made a list of best aquarium thermometers 2019 to help you choosing the best one matching your need.

In the absence of a thermometer, fluctuations in temperature may remain unnoticed by the owner of the aquarium. Aquarist should constantly monitor the water temperature in the aquarium. The thermometer is an absolutely necessary measuring device for him. On the failure of the temperature in the aquarium should be known as soon as possible and immediately take action.

Review of Best Aquarium Thermometers

To save your lots of money and times I have done deeply research and reviewed top ten best aquarium thermometers which you can try to buy to maintain accurate temperature for your aquarium. You can also take more information about each thermometer before buying best one.

Comparison Table for Top Ten Aquarium Thermometers

Now it’s time to get into the details of each and every Best Aquarium Thermometers. To be frank, all of them has the potential to be the leader of the list. We have discussed every item so deeply to create a clear picture on your mind which will create your purchase decision a lot easier. Let’s jump into it.

Zacro LCD Digital Aquarium Thermometer

Our Rating

The Zarco digital thermometer is an attractive and favorable among most of the aquarium hobbyist making it one of the most versatile thermometers. It has two sections, the probe and LCD monitor. The LCD monitor is the best component of this advanced aquarium thermometer. 

It is an extensive and simple to peruse which makes it perfect for those keeping fish. So you needn’t bother with an amplifying glass when attempting to check the temperature. The screen or display unit is genuinely vast however the entire thermometer is in reality truly little which make it is extremely versatile and simple to store in small spaces.

This thermometer is controlled by one single and long lasting LR44 button cell battery. It can measure the temperature which extends between – 50 degrees Celsius and +70 degrees Celsius. It gives extremely exact outcome and it can measure temperature to inside +/ – 0.1 degrees.

The Zarco can be mounted with the assistance of suction container to the glass surfaces of your tank. The probe unit has its own particular suction container that can slide up or down the probe’s wire so you can suction the probe inside the tank either high or low, whatever your preference.

Key Features of Zarco Digital Thermometer

• It has easily readable LCD monitor;
• It has compact design for discrete use;
• It can measure the temperature which goes between -50 degrees Celsius and +70 degrees Celsius.
• It gives very exact result;
• It is powered by one single and long lasting LR44 button cell battery;
• Operating temperature ranges between -10 degree Celsius and ~ +50 degree Celsius;

Technical Details of Zarco Digital Thermometer

• Size: 2″ x 1.25″
• Color: Black
• Batteries: LR44

Zarco Digital Thermometer Package Contents

• Battery: 1
• Digital Thermometer: 1
• Probe: 1

Pros

• It has submersible Waterproof Probe unit;
• LCD monitor for taking easy readings.
• It has long lasting suction cup to hang it on the side;
• It is small and compact in nature.
• Portable due to small size and easy to store in small spaces.
• It is powered by one single LR44 button cell battery.
• Installation is very easy;
• It is perfect for smaller tanks and you can take temperature reading on the spot;

Cons

• Only Probe unit is Waterproof
• It has no back-light for the LCD monitor;
• No alarm system;

Generally speaking, Zacro LCD Digital Aquarium Thermometers have high quality sensor probe unit which gives persistent temperature readings. For this situation this Zarcon certainly makes for a good choice among the pet fish keepers. In the market it is available with black in color and you can purchase it single or twice as a package with sensible cost.

HDE Digital Aquarium Thermometer

Our Rating

The HDE Digital Aquarium Thermometer is a well known device among the aquarium specialist because of its exceptionally attractive appearance. It has easily readable and substantial LCD monitor and submersible probe unit. It is fueled on by utilizing easy to replace batteries that can be found in many stores.

This type of thermometer should not be connected to with electric attachment that limits the danger of electrical shock to the fish inside aquarium. It can measure the temperature which runs between – 50 degrees and +70 degrees Celsius. It gives exceptionally precise outcome and it can quantify temperature to inside +/ – 0.1 degrees.

Key Features of HDE Aquarium Thermometer

• It has easily readable LCD monitor;
• It can measure the temperature which goes between -50 degrees Celsius and +70 degrees Celsius.
• It has submersible probe to measure the aquariums temperature;
• It gives very exact result;
• It is powered by easily replaceable single LR44 button cell battery which lasts a very long time;
• Operating temperature ranges between -10 degree Celsius and ~ +50 degree Celsius;

Technical Details of HDE Aquarium Thermometer

• Size: 2″ x 1.25″
• Color: Black/yellow
• Batteries: LR44

HDE Aquarium Thermometer Package Contents:

• Battery: 1
• Digital Thermometer: 1
• Probe: 1

Pros

• Submersible Waterproof Probe unit with long cable is present;
• Easily readable LCD monitor;
• Long lasting suction cup that is used to hang on the side;
• Portable and easy to store in small spaces.
• It is powered by one single LR44 button cell battery;
• It gives exact readings;
• Installation is easy;
• It is perfect for smaller tanks;

Cons

• It is made using plastic materials;

All things considered, it is a magnificent aquarium thermometer that gives you accurate temperature readings. To keep your fish sound and upbeat, you should request to purchase this ravishing advanced aquarium thermometer. In the tech market it is available and you can purchase it as 1-pack, 2-pack and 3-pack with reasonable price.

CNZ Digital LCD Thermometer

Our Rating

CNZ Digital LCD Thermometer is an amazingly precise device to measure temperatures in your aquarium. This system incorporates power button, mounting suction containers, replaceable battery, in addition to a 39 inch long cable with the temperature reading probe at the head, making it extraordinary for bigger aquariums.

This thermometer is a perfect for checking temperature in Aquarium or terrarium. It has easily readable LCD monitor and probe unit. It can measure the temperature which extends between – 10 degrees and +140 degrees Fahrenheit. It gives extremely precise outcome and it can measure temperature to inside +/ – 1.5 degrees Fahrenheit.

This type of thermometer is worked by utilizing replaceable battery and should not be connected to with electric attachment that limits the danger of electrical shock to the fish inside aquarium. Additionally, it is made using high quality materials but should be covered during operation to prevent water damage.

Key Features of CNZ Digital LCD Thermometer

• It is ideal for monitoring temperature in aquarium or terrarium;
• It has easily readable LCD monitor;
• Probe unit with long cable;
• Portable and easy to store in small spaces;
• It is powered by one single replaceable cell battery;
• Installation is easy;

Technical Details of CNZ Digital LCD Thermometer

• Product Weight: 9 g;
• Product measurement: 11.7 x 6.9 x 1.8 cm;
• Batteries: 1 Battery;
• Package includes: 1x CNZ Digital Thermometer

Pros

• It has easily readable LCD monitor;
• Fahrenheit and Celsius reading;
• It gives extremely exact reading;
• It is ideal for aquariums and terrariums;

Cons

• It should be covered during operation to prevent water damage;

All things considered, CNZ Digital LCD Thermometer is a brilliant device which gives you exceptionally correct temperature reading. Moreover, it is made utilizing superb materials which make it exceptionally famous among the aquarium enthusiasts. We prescribe you to buy this thermometer to make tank condition safe. You can buy it as single, 2-pack and 6-pack with sensible cost.

Zoo Med Terrarium Thermometer

Our Rating

The Zoo Med Digital Terrarium Thermometer is an extremely appealing device for taking temperature reading. It is suitable for aquariums, terrariums and reptile and gives perfect reading. This sort of thermometer has a remote sensor probe unit that read in or out of water.

It gives temperature reading in Fahrenheit or Celsius that extends from – 10° to 140°F (- 23° to 60° C). You can mount it effortlessly inside or outside terrarium with included suction containers. To get result effectively simply put the probe unit, turn on the display unit and you can see the temperature at a glance.

Key Features of Zoo Med Digital Terrarium Thermometer

• It is perfect for aquariums, terrariums and reptile;
• It has easily readable LCD monitor;
• It measures the temperature which ranges from 10°F – 140°F (-23°C – 60°C);
• It has water resistant temperature probe;
• It includes mounting suction containers and single LR44 1.5v battery;
• Manufacturer Warranty: 1-year;

Pros

• Installation is very easy;
• Gives accurate reading;
• It is used in terrariums, aquariums or reptile incubators;
• It gives reading both in Fahrenheit and Celsius scale;
• It is very portable;

Cons

• LCD display unit should be placed in dry place.

All things considered, the Zoo Med Digital Thermometer is an exceptionally well known and propelled sort device for taking precise temperature reading. It is reasonable for aquariums, terrariums and reptiles hatchery. We prescribe you to get it for your aquarium,terrariums and reptiles hatchery.

Leegoal Digital Aquarium Thermometer (Black)

Our Rating

Leegoal Digital Aquarium Thermometer is an extremely keen device. You can take precise temperature readings from your aquarium effectively utilizing this thermometer. It has a huge, easily readable LCD monitor to see the temperature reading effectively. It accompanies suction container that enables you to place to any smooth surface.

This type of thermometer bears On/Off button to save battery power. It also has submersible probe unit to monitor the temperature in wherever. The LCD monitors or display unit should be covered to prevent wet because it’s not waterproof.

Key Features of Leegoal Digital Aquarium Thermometer

• It has easily readable LCD monitor;
• It has submersible probe to take reading in any place;
• It can measure the temperature which ranges from -50 ° C~ +70 ° C ( -50 ° F~ +158 ° F);
• It gives very accurate result and it can measure temperature to inside +/- 0.1 degrees;
• It has power button to save battery power;
• It has external probe unit with 36 inch insulated wire;
• It gives result both in Fahrenheit and Celsius;

Technical Details of Leegoal Aquarium Thermometer

• Temperature resolution: 0.1 ° C or F
• Power : 1.5 VDC
• Body Size: 59 X 37 mm;
• Monitor size: 26 X 13 mm.
• Product weight: 0.02 pounds
• Package Size: 3.3 x 1.1 x 1.1 inches
• Package weight: 0.02 pounds;
• Package Size: 3.3 x 1.1 x 1.1 inches
• Units in Package: 1;

Pros

• It has probe unit with 36 inch insulated wire to take temperature reading;
• Installation is very easy;
• It gives Celsius and Fahrenheit readings;
• It is inexpensive;

Cons

• It has no backlight system to see result during night time;
• No alarm system;
• Display unit is not water proof;

Over all, Leegoal Digital Aquarium Thermometer is an exceptionally well known thermometer among the pet fish keepers because of rightness and attractive appearance. We recommend you to purchase this thermometer to make tank condition safe.

AODE®Digital LCD Aquarium Thermometer

Our Rating

AODE® Digital LCD Thermometer is an amazingly precise device to measure temperatures in your aquarium. This system incorporates power button, mounting suction containers, replaceable battery, in addition to a 90 cm long cable with the temperature reading probe at the head, making it extraordinary for bigger aquariums.

It is a perfect for checking temperature in Aquarium. It has easily readable LCD monitor and probe unit which can measure temperature both in Fahrenheit or Celsius. It can quantify the temperature which runs between – 50°c ~ + 70°c. It gives extremely precise outcome and it can measure temperature to inside +/ – 0.1 degrees C.

It is worked by utilizing LR44 button cell battery and should not be connected to with electric attachment that limits the danger of electrical shock to the fish inside aquarium. Moreover, it is made utilizing amazing materials but should be covered during operation to prevent water damage.

Key Features of AODE® Digital LCD Thermometer

• It is made using high quality materials;
• It has easily readable LCD monitor;
• It shows result both in Celsius and Fahrenheit;
• It is powered by one LR44 button cell;
• It measures the temperature which ranges from -50°c ~ + 70°c;
• It gives very accurate result and it can also measure temperature to within +/- 0.1 degrees C.

Technical Details of AODE® Digital LCD Thermometer

• Product measurement: 2.5 x 2.2 x 0.7 inches
• Color: Black
• Brand: AODE
• Product weight: 0.3 ounces;

Pros

• It has easily readable LCD monitor and probe unit with 90 cm long cable;
• It gives very accurate result both in Fahrenheit and Celsius;Installation is easy;
• It is portable;
• It is powered by one LR44 button cell battery;
• You can take temperature reading on the spot;

Cons

• LCD display unit does not have cover to prevent damage;
• It has no alarms system;
• Result can be difficult to read in the dark due to lack of backlight on display unit;

Different colors of AODE® Digital LCD Thermometers are sold in the market which include the black and yellow colors. You can buy it 1-black color, 2- black color, 1-black & 1-yellow color or 2-yellow color at a time. All these have same features and benefits.

Overall, it is a very familiar and highly recommended in the fish keeping community due to its high performance and gorgeous coloration. To keep your water temperature stable and get unlimited service, it is highly recommended to buy this gorgeous and high performance AODE Digital LCD thermometer.

TOOGOO Digital LCD Aquarium Thermometer

Our Rating

TOOGOO Digital LCD thermometer is a noteworthy thermometer. You can take examining temperature from your aquarium adequately using this automated thermometer. It has easy to read and 25mm X 12mm LCD screen that energizes you to get temperature readings easily. The probe unit has 1 meter cable which is submerged into water of the aquarium.

It can measure the temperature which goes between – 50° and + 70° Celsius. Also, it is made utilizing top notch materials but should be covered during operation to prevent water damage.

It is fueled by a DC 1.5V LR44 button battery and should not be associated with electric connection that restricts the risk of electrical shock to the fish inside aquarium. To ration control, you can turn off the display and simply turn it on when you need to see the temperature.

Key Features of TOOGOO Digital LCD Thermometer

• It has easily readable LCD monitor;
• It has submersible probe unit with 1 meter cable to monitor the temperature in any place;
• It can measure the temperature which ranges from -50 ° C~ +70 ° C ( -50 ° F~ +158 ° F);
• It is powered by a DC 1.5V LR44 button battery;
• It gives result both in Fahrenheit and Celsius;

Pros

• It is inexpensive and durable;
• It has power on/off button to conserve battery power;
• It has a compact design;
• It is portable due to small and lightweight;
• It gives accurate readings.

Cons

• It has no back-lighting system;

After all, it is a very smart digital thermometer among the aquarium fish keepers due to its high quality performance and accuracy. For correct temperature examining from your aquarium, you can absolutely depend upon this TOOGOO Digital LCD thermometer.

CoZroom LCD Digital Aquarium Thermometer

Our Rating

CoZroom LCD Digital Aquarium Thermometer is a little and smaller planned aquarium thermometer. This will empower you to monitor the water temperature and keep your fish in their best state. It has considerable propelled LCD monitor or display unit. You can without a doubt watch the temperature readings on the LCD display unit.

It is fueled by two batteries and it presents easily. You basically need to append the display unit outside the fish tank using the suction cups at that point submerge the probe into the water.

This thermometer is emphatically created with a solid plastic material to give a tough execution. It can take temperature reading which goes between – 50 and 70 degrees C.

Key Features of CoZroom Digital Aquarium Thermometer

• It has suction cups for easy installation;
• It can measure the temperature that ranges from -50 to 70 ℃ with an operating temperature from -10 to 50℃;
• It gives very accurate result and it can measure temperature to inside +/- 0.1 degrees C.
• It is powered by two button batteries.

Product of CoZroom Digital Aquarium Thermometer

• Product weight: 0.02 pounds;
• Product measurement: 0.79 x 5.12 x 5.12 inches;
• Package weight: 0.02 pounds;
• Package Size: 2.9 x 1.2 x 1.2 inches.

Pros

• It has easily readable LCD monitor;
• Installation is very easy;
• It gives accurate temperature reading;
• Long lasting performance;
• It is small and compact design which make it portable;
• It does works well in various environmental conditions;

Cons

• The display unit does not have any cover to prevent damage;

In the market it is available 3 in pack with black color with sensible cost. Overall, CoZroom LCD Digital Aquarium Thermometer is a very popular among the aquarium enthusiasts because it has a high exactness of 0.1 degrees, and this ensures the water temperature is right for the fish.

RISEPRO Digital Water Thermometer

Our Rating

RISEPRO Digital Water Thermometer is perfect for taking temperature reading from Aquarium. Installation is easy and you can utilize it for marine and freshwater aquarium. It is additionally an ideal instrument for observing the temperature for different types of reptiles such as lizard, turtle etc.

The thermometer gives a wide range and exact temperature reading which goes from – 58 to 158 degrees Fahrenheit with a correctness of +/ – 1 degree. It is additionally a standout amongst the most adaptable available, enabling you to change into any tank that you have to check the water in, regardless of how enormous or little the tanks are.

Key Features of RISEPRO Digital Water Thermometer

• Easily readable LCD monitor with sensor probe;
• It measures the temperature reading which goes between -58.0 and 158.0 degree Fahrenheit (-50.0 and 70.0 degree Celsius) with correctness +/- 1 degree Celsius;
• It is appropriate for different water types such as marine or fresh water, tap water etc.
• It is also perfects for monitoring the temperature for lizard, turtle etc.
• Installation is easy;
• It is operated by one LR44 button cell battery;

Specification of RISEPRO Digital Water Thermometer

• Body color: Black;
• Body size: small;
• Product measurement: 5.8 x 3.8 x 1.5 cm;
• Product weight: 0.3 ounces;
• Brand: Risepro;
• Temperature resolution: 0.1°C;
• Correctness: +/- 1°C;
• Switch: Celsius (°C) and Fahrenheit (°F);
• Battery: Two AG13 button cell battery;
• Probe cable length: 1 meter;

Pros

• It does best in all sized aquariums;
• It is also perfect for reptiles;
• It gives accurate temperature reading;
• It is portable due to small size;
• It has easily readable LCD monitor;
• It has suction cup which helps to attach to the outside of the tank;
• Installation is easy;

Cons

• The LCD monitor or display unit is not water proof;

After all, Risepro digital water thermometer is a renowned and adaptable thermometer that functions excellently with various sorts of fish tanks such as marine or freshwater and give you the most exact water temperature reading.

Marina Floating Thermometer

Our Rating

Marina Floating Thermometer is a high caliber, moderate and dependable thermometer because of their exact temperature readings. It works in both freshwater and saltwater tanks and is made to float in a vertical position. It additionally has a suction cup to join to the aquarium walls.

This therdoesn’t have any LCD display or probe units to give results. In this system mercury is utilized to measure the temperature. It is very dependable thermometer that does not go offline. It also has safe zone indicators that help to demonstrate the perfect temperature range for most tropical fish.

Key Features of Marina Floating Thermometer

• It is perfect for both marine and freshwater;
• It bears optional suction cup;
• Celsius and Fahrenheit reading;
• It provides accurate readings;
• Temperature reading is easy to read due to labeled with large sized fonts;
• It has safety zone indicator that helps to protect fish from unsafe temperature;

Specifications of Marina Floating Thermometer

• Color: Multicolor;
• Brand: RC Hagen;
• Product weight: 0.057 pounds.

Pros

• It is designed with a safety zone indicator for most tropical fish;
• It does not need batteries to operate;
• It provides very accurate temperature readings;
• Inexpensive;

Cons

• It is made using glass and fragile;

Generally speaking, Marina Floating Thermometer allows accomplishing the best temperature reading from your aquarium. To get better service and execution, it is exceptionally prescribed to purchase this basic and dependable thermometer for your aquarium.

Types of Aquarium Thermometers

To monitor the water temperature in the aquarium you will need a best aquarium thermometers. They also come in different types. I advise you to purchase a thermometer which is specially designed for aquariums. In pet stores you can find different types of aquarium thermometers, but the most popular thermometer is a LCD thermometer, digital thermometer, and finally floating or standing thermometer.

LCD Thermometer or Liquid Crystal Display

Much more convenient thermometers are liquid crystal display thermometer (LCD). It is also called stick on thermometer which is the most widely used and the most popular thermometer in freshwater aquariums. A huge plus of such a thermometer is its appearance.

These types of thermometers have a vertical or horizontal strip which can be stacked on the outside of the aquarium glass wall and in a place where they do not obstruct visual beauty. The strips have both Fahrenheit and Celsius readings or just the Celsius and the Fahrenheit scales. Strips are very easy to use and are unbreakable.

LCD thermometers show result very accurate, it is versatile, easy to use and inexpensive but it is very unpretentious. It is formulated to change temperature from -22 to +248° F (-30 to 120 °C), and can be sensitive enough to detect changes as small as 0.2° F. 

This type of thermometer should not be placed in such a place where it receive direct sun light or near a heating or cooling vent.

Pros

• It is cheap;
• It is versatile and easy to use;
• It is non-breakable;
• You can use it in multiple places;

Cons

• During low lighting condition it is hard to read your result;
• It has no alert function;
• It shows less accurate result than digital thermometer;

Floating or Standing Thermometers

Floating or standing thermometer has a simple glass tube which is filled with mercury. This type of thermometer is placed inside the aquarium which gives a direct measurement of water temperature.

Most of the floating thermometers have a suction cup attached which allows you to attach to the inside of your aquarium. This type of thermometer does a good job of reading the temperature accurately. It comes in several styles including:

• Floating style: It floats on the aquarium water;
• Sticking style: It sticks to tank inside with the help of rubber sucker or suction cup;
• Hanging style: It hangs on the aquarium wall with a clip;
• Sinking or standing style: It sinks and stands on the bottom of the aquarium due to weight. The standing models allow for a temperature reading near the bottom of the tank.

Floating thermometer is a great choice for all the aquarium hobbyists and it provides you an actual result of your aquarium temperature. This type of thermometer is very cheap and most of these thermometers are made of glass which makes them considerably more fragile than the other types of thermometers. But some are made of plastic while others are made of stainless steel and they last for a very long time. This type of thermometer should be used for small to moderate aquarium. When you use in a large tank, you should use this thermometer in several places of the aquarium.

Pros

• It is cheap;
• It can be placed in several places;It lasts for long time;
• It provides accurate reading of temperature;
• Some provide easily view-able reading;

Cons

• It has no alert function;
• It gives less accurate result than digital thermometer;
• It is breakable when you use glass made thermometer;
• Scale is small and difficult to read

Digital Thermometers

It is a rectangular in shape with a small LCD screen. It is very attractive and shows smart appearance. It shows result as Fahrenheit or Celsius. Digital thermometers can be mounted and moved when and where you desire. They are fully sealed, protected from moisture, equipped with batteries with a long life and have a strictly defined error. They have many advantages and provide accurate temperature indicators for a long time. Such thermometers are very convenient for use in nano aquariums. It shows result very accurately. It is a relatively recent innovation.

Most of these thermometers are more expensive than conventional ones, but some of them are sold at a very reasonable price. Digital thermometer does contain probe and digital display unit. The probe is placed in the tank with the help of connector and digital display unit is placed outside of the tank which shows reading. Some digital thermometers have a cable which connects the probe to the display unit but others connect wirelessly.

Digital type of thermometers has several models with varying cord length. Some have audible alert function which makes sound during the result falls below or above the specified limits. Some include a built in light which help you see the reading in a dark room but some models measure the room temperature and include a clock also. During choosing a style, you should check the probe and cord length.

You might also love to read our review of Best Aquarium Air Pump.

Pros

• It gives result most accurately;
• It lasts for long time;
• It has digital display unit;
• It gives result which is easy to read;
• Some models have alert function and make sound when temp is out of range;
• Some include a built in light which help you see the reading in a dark room;
• Some have extra clock unit;
• It can show result as Fahrenheit or Celsius;
• It is not influenced by ambient room temperature;

Cons

• They are more expensive;
• It requires batteries to operate;

How to Choose the Best Aquarium Thermometers?

Not all aquarium thermometers are sufficiently precise, so if there is a decision when purchasing the best aquarium thermometers, at that point it should surely be utilized. Put every one of the thermometers before you and see what temperature they appear. It is important to look over those that show the “opinion of the majority”. Products enlisting a higher or, then again, low temperature, don’t have to purchase.

Buy products only from known manufacturers of aquarium equipment with reliable model. When buying you should prefer the best aquarium thermometers with a brightly colored column which is better seen in the water.

Uses of Thermometer in Your Aquarium

• Thermometer tracks water temperature in your aquarium;
• It distinguishes any issues in your aquarium identified with water temperature variances;
• Thermometers confirm you that the water temperature of your aquarium is perfect for fish;
• Thermometers announce you that water quality parameters that depend on temperature are suitable for your aquarium inhabitants;

Final Verdict

Types of Aquarium Thermometers

Aquarium thermometer is a basic device for freshwater and saltwater aquariums which significantly affects your aquarium inhabitants. Changing or unsatisfactory water temperature can negatively affect both fish and plants. This important device gives exceptionally exact temperature readings which are vital for the fish and plants in your aquarium. We clearly prescribe you to purchase the best aquarium thermometers from the above choices, which provide genuinely exact water temperature reading in your tank that is essential for keeping your fish alive.