Can Cardinal Tetra Live In Coldwater? Can They???

Cardinal tetras are one of the most popular aquarium fish among freshwater aquarists. It is also famous as cardinalfish or red-eye tetra and belongs to the Characidae family. They are native to the Amazon River basin. But now they are present in other rivers of Central and South America. So, do you think Cardinal tetra can live in coldwater?

Cardinal tetras are not cold water fish. They need warm temperatures of at least 70 degrees Fahrenheit (21 C). If the tank is too cool, they will become sluggish and may even die if left in cold conditions for an extended time.

If you are new to fish keeping, then the optimum temperature of the tank is a crucial thing to consider. We will answer all these questions about whether Cardinal tetra is coldwater fish or not in detail below. So, keep reading.

What Is The Natural Habitat Of Cardinal Tetra?

The natural habitat of cardinal tetra is in tropical South America. They are primarily present in the Rio Negro area, which has warm water. In the wild, Cardinal tetras live in an environment with high humidity and dense vegetation. These freshwater fish usually swims around in a slow-moving river, which has a soft substrate.

The water conditions of their natural habitat are typically complex and acidic. In the wild, the pH of cardinal tetra’s water is usually between four and six. Besides this, the temperature is generally between seventy and eighty degrees Fahrenheit.

Cardinal tetra needs water conditions that are similar to its natural habitat to survive for long periods.

Can Cardinal Tetra Live In Coldwater?

No, cardinal tetras cannot live in cold water. If the temperature is below 15 degrees Celsius, they will die. So it’s best to keep them at around 22 – 27 degrees C with a pH of about neutral or slightly acidic and hardness of soft to medium-hard.

Cardinal tetras are initially from the tropical rainforest regions in South America and need hot water conditions to survive. If you keep them in cold water, it will cause their immune system to fail. This makes them vulnerable to diseases, infections, or parasites that can even kill them quickly.

The minimum temperature that Cardinal tetras can tolerate is about 18 degrees Celsius. If you want to keep your tetras in colder water, it’s best to get a heater and make sure the temperature is at least 20-22 degrees Celsius, which will mimic their natural tropical habitat for them.

Why Should Not You Keep Cardinal Tetra In Coldwater?

Cardinal tetra is a tropical fish, and they will not survive in cold water. So if you put them into an aquarium that has colder water, they will die quickly.

Some of the reasons why it is a bad idea to keep Cardinal tetra in cold water are:

  • Coldwater increases stress in the Cardinal tetra, which can lead to disease outbreaks.
  • The lifespan of your cardinal tetra reduces if you put them into cold water. It is because the metabolism of these fish slows down when it is they are in a colder environment.
  • Cardinal tetras cannot get enough oxygen in cold water, so that they will have trouble breathing.
  • Cardinal tetras are more prone to disease when they live in cold water. So putting them into aquariums with more freezing temperatures is a bad idea.
  • Keeping them in cold water makes them aggressive. Thus, Cardinal tetras will start fin nipping and bullying other fishes.
  • In addition to that, their swim bladder could have problems when they are in cold water.

When the temperature of your aquarium is lower than usual, you will need a heater and an air pump because it needs oxygenated water for this fish species.

How To Keep Cardinal Tetras’ Tank Warm In Cold Environment?

Cardinal tetra fish are prevalent among aquarium hobbyists. They look stunning in freshwater tanks with lots of plants, but their popularity comes at a price. They need special conditions to survive and thrive, and optimum temperature is the most crucial one above all.

However, some of the ways to maintain the tank’s optimum temperature in cold surroundings are:

Use An Aquarium Heater

One of the most common ways to keep cardinal tetra fish tanks warm is using an aquarium heater. Different models are available on the market, so it’s pretty simple to have one that perfectly fits your needs and requirements.

Aquarium heaters come with a thermostat that you can turn off once water heats up enough. You can set the temperature, and that’s it – you don’t even need to monitor your tank daily.

Just make sure not to place the heater somewhere the glass might break, so use thermometers as well if necessary.   

Add Thermometer To Your Aquarium

Cardinal tetra fish are pretty sensitive when it comes to water temperature. If the environment is not close to their optimal one, they’ll behave strangely or even die of stress.

That’s why most aquarists recommend buying a thermometer and place it in your tank so that you can monitor the water temperature every day at least once. Then, you have to do some simple math and deduct the current water temperature from the desired one.

If there’s a massive gap between these two, you might want to consider buying an aquarium heater as soon as possible.   

Install A Submersible Pump

It is one of those rare air pumps with heating capability, so you need to plug it in and let it do its job. You should also turn off the water pump if there’s any tank leak because the air pump might suck in air and stop working.

Use A Heated Filter

Some aquarium filters have the heating capability so that you can install them instead of the standard model. Just make sure that the filter’s wattage is not too much for your tank to handle, as this will overheat water very quickly. However, be attentive. Such models are not very common.

Use A Heated Sponge Filter

The third option is to use the heated sponge filter, which you can buy from your local pet store or online retailer. These are usually suitable for tanks up to 50 gallons in size, and they work great because of their powerful suction force that draws water into it through a tube. The sponge heats up with the help of an electrical cable that you need for the plugin.

Be Careful About The Size Of Your Tank

If you want to keep cardinal tetra fish healthy, it’s important to maintain their optimum temperature. However, if your tank is small and has a limited surface area for water evaporation, then this might not be possible.

So, if you live in a cold environment and want to keep cardinal tetra fish healthy, then the thing is that they need warm water. Suppose your tank’s surface area for evaporation or room temperature is not high enough. In that case, it won’t be easy to maintain this species of tropical fish at their optimum health condition.


Can Cardinal Tetra Live In Hot water?

No, Cardinal Tetra cannot live in hot water. If the temperature is too high, it may die or become ill. The maximum temperature that these fish tolerates is around 33.0°C or 77-90°F, so it is best to keep them around that range if you can stand the water being a bit cooler than usual!

Can I Breed My Cardinal Tetra?

Yes, you can breed them. But breeding is not as easy as it seems, so prepare yourself before.  Breeding cardinal tetras take a long time and a lot of patience and suitable conditions to allow them to breed.

Can I Put My Cardinal Tetra In A Community Tank?

Yes, you can put cardinal tetras in a community tank. Still, it is important that if the tank has other fish, then make sure that they do not nip at or eat your cardinal tetras and make sure there are no different types of tetra living in the community tank because this could cause competition for food.


In conclusion, Cardinal tetras can tolerate a slight fluctuation in their water temperature. Therefore, they can live in a coldwater aquarium if the temperature is not below 70 degrees Fahrenheit. But ensure that the tank has a regular water circulation to ensure to keep the oxygen levels high.

It’s important to keep them fed, which will help with their coloration and health. Cardinal Tetras also respond well when kept with other varieties of tetras. It would be an excellent excuse to create another aquarium.