Do Cardinal Tetras Need A Heater: An Ultimate Guide

Cardinal Tetras are one of the most popular aquarium fish. You can keep these fish with other community fishes in an ideal tank with proper care and maintenance. However, the question among most fish keepers is, do Cardinal tetras need a heater?

Cardinal Tetras do need a heater. These fish need to live in water between 75 and 80 degrees Fahrenheit (25-27°C). Cardinal tetra fish will die if the temperature drops below 50°F (15°C) or rises above 86°F (30°C).

If you are thinking of keeping cardinal tetras, many questions can make any person’s head spin! But don’t worry- we’re here to give you the answers.

Do Cardinal Tetras Need A Heater?

Cardinal Tetras are one of the most popular and beautiful fish. Cardinal tetras come from South America, specifically Brazil, Guyana, and Venezuela. They typically live in gentle moving waters such as slow-moving rivers or forest streams that have a lot of leaf litter on the bottom where they can hide.

Moreover, like most fish, this ish also needs a specific environment to survive. Thus, Cardinal tetras need a heater to survive. Cardinal tetras are tropical fish and require warm water between 72-78 degrees Fahrenheit (22-26 Celsius).

If the temperature falls outside of that range, they will become stressed or sick. Therefore, if you want your Cardinal Tetra Fish healthy, they need an aquarium with appropriate heating equipment.

Why Do Cardinal Tetras Need A Heater?

Generally, Cardinal tetras are tropical fish and cold-blooded in nature. So, they require a higher temperature in the water. Therefore, Cardinal tetras prefer a tank with temperatures between 77-83°F, which you cannot attain without a heater.

Moreover, few points that will clarify the need for a heater for cardinal tetras are:

Low Temperature Can Cause Hypothermia

Cardinal tetras have a normal body temperature ranging between 77-83°F, which is the optimum range for staying healthy. But when you keep Cardinal Tetras in the water below 70°F, they can develop Hypothermia and eventually die due to the effects of low temperatures.

Heat Can Help Cardinal Tetras To Fight Against Diseases

Cardinal tetras are usually prone to diseases because of their sensitive immune system. But when they stay at higher temperatures, it helps them fight against the disease.

Cardinal Tetra Breeding Is Easier In Warm Water

Cardinal tetras can breed in water with a normal aquatic pH level between Slightly Acidic and Slightly Alkaline. But when they stay in warm water, their breeding becomes easy as the eggs hatch faster and larvae become healthier.

Less Oxygen In Cold Water

Cardinal tetras are native to South America, where the water is warm. This is because Cardinal Tetra’s eggs need warmth for spawning and the growth of larvae. Also, Cardinal tetra’s prefer water with plenty of dissolved oxygen present in warmer waters than colder ones.

Water With Higher Temperature Makes Cardinal Tetra More Active

Cardinal tetras become more active and energetic when they stay in the water with higher temperatures. These fish tend to spend most of their time on the surface of the tank and breath air directly from the atmosphere. Keeping them at a lower temperature reduces this behavior and their activity level due to slow metabolism.

What Factors Will Increase The Need Of Cardinal Tetras Heater?

Few factors will increase the need for a Cardinal Tetras heater:

Poor Fish Tank Condition

Cardinal tetras tend to be very sensitive. Therefore poor water conditions can cause disease and low oxygen levels in Cardinal Tetra’s home tank. Also, Cardinal tetras require more dissolved oxygen than other tropical fish, and Cardinal Tetra’s heater helps in maintaining the required temperature.

Poor Cardinal Tetras Health

If your Cardinal tetra is suffering from any disease, you should increase the water temperature to recover it. Generally, warmer water has a better treatment option for Cardinal tetra’s diseases than colder ones because most fishes are more active in warm waters. They consume more oxygen, too, which can help them heal faster.

Age Of Cardinal Tetras

Cardinal tetra fishes are susceptible, and they need more warmth in the water. If your fish is less than one year old, then its body will not cope with the colder temperatures of the home tank, and you should always keep a heater for it. But if your Cardinal tetra is more than one year old, it can survive with lower temperatures, but Cardinal tetra’s heater will help them stay active.

Lighting Condition

Cardinal Tetras are more sensitive towards the light. Therefore, too much lighting condition of the tank might cause stress on your fish, and they may not be able to eat properly, which further leads to low oxygen levels, and Cardinal Tetra’s heater will help them stay active. But if your fish is less than one year old, then its body will not cope with the colder temperature of the home tank, and you should always keep a heater for it.

What Type Of Heater Should You Use In Cardinal Tetras Tank?

Cardinal Tetras need a heater in their tank which means you have to choose the best Cardinal Tetra Heater. The Cardinal tetra is one of the most popular tropical fish that are available for sale. They are peaceful and do not get too large, making them great for smaller aquariums. They prefer warmer water temperatures around 70-86 degrees Fahrenheit or 21-30 degrees Celsius.

However, the things you must consider when you get the heater for Cardinal tetras are:

  • It would be best if you made sure the Cardinal Tetra Heater you choose fits your aquarium size.
  • Do not buy cheap Cardinal Tetras tank heaters. They often malfunction and can cause injury or death to your fish.
  • It would help make sure the Cardinal Tetras tank heater you choose has a thermal overload protector.
  • Some Cardinal Tetra Heaters have their own thermostat and help control water temperature inside your aquarium.
  • Make sure that Cardinal Tetras tank heater is adjustable to fit into different sizes of tanks with different temperature settings.

Having a Cardinal tetra heater in your aquarium is necessary as they help maintain the water temperature. Without it, Cardinal tetras can’t survive and will die within a couple of days. However, you need to choose the heater carefully because this small fish cannot tolerate cold temperatures, which you should avoid at all costs if you don’t want to put Cardinal Tetras at risk.

What Are The Best Heaters For Cardinal Tetras?

Cardinal Tetras are an omnivorous species of fish which means they eat both meat and plants. Therefore, Cardinal Tetras will not only look better in the tank, but they also stay healthier if you provide them with a heater or at least maintain their water temperature around 25 degrees Celsius (77 Fahrenheit).

Some of the examples of heater best for Cardinal tetras tank are:

Aqueon Pro Heaters

Aqueon Pro Heaters can heat up to a 100-gallon tank and make it of titanium. In addition, it has adjustable temperature control, making it easy for Cardinal Tetra owners to keep the water constant.

Aqueon Pro Heaters are one of the best Cardinal Tetras heater options because they have an automatic shut-off function if there is some power outage or malfunctions, so you don”t have to worry about them Cardinal Tetras tank water getting too cold.

Tetra HT Submersible Aquarium Heaters

The Tetra HT submersible aquarium heater is best for Cardinal tetras because it has an adjustable temperature dial. The adjustable dial is very convenient because Cardinal Tetras owner can control their Cardinal Tetras tank temperatures instead of having a one-size-fits-all approach for every 100-gallon Cardinal Tetras tank.

This Aquarium heater provides an automatic shut-off mechanism to prevent overheating and power outage malfunctions. Owners can feel safe knowing they have a functional water heater to keep Cardinal tetras healthy and safe.

Aqueon ProMax Heater 50W

These Aqueon pro max heaters are the most reliable heaters on the market today and the best Cardinal Tetras tank heater. They are perfect for Cardinal tetra owners who want to keep Cardinal Tetras in 100-gallon tanks because it has the ability to heat up to 50 gallons of water with ease.

The Aqueon pro max aquarium heaters provide an automatic shut-off mechanism so the owner won’t worry about tank overheating. In addition, the tank water heater has a shatterproof glass exterior with an easy-to-read temperature gauge, making it very convenient for Cardinal tetras.

If the owner is looking for a reliable 100% shatterproof Cardinal Tetra fish tank water heater,  Aqueon ProMax Heater 50W is a great choice.

Can I Keep Cardinal Tetras Without Heater?

Cardinal Tetra is a peaceful fish. They are great community tank mates for other tropical freshwater aquarium fishes. Cardinal tetras can be very compatible with most of the inhabitants of your freshwater aquariums. However, it doesn’t mean that you do not need to provide heating or cooling equipment when you plan to keep Cardinal Tetras at room temperature.

However, if you succeed in providing an appropriate environment for Cardinal tetras, you can keep Cardinal Tetras without Heater.

For this, you must keep your Cardinal tetra’s tank in:

  • Room Temperature 12°C~18°C (54°F~64°F)
  • Ensure that there is enough space for Cardinal tetras to move.
  • Ensure that Cardinal tetras get enough oxygen in the water.
  • Make sure to provide Cardinal Tetra’s tanks with plenty of hiding spots, e.g., driftwood, plants, or rocks where Cardinal tetras can hide when needed.
  • You can do this by providing Cardinal Tetra’s tanks with gentle filtration only.

Cardinal tetras are relatively hardy fish, they can adapt to your home environment, but an ideal tank is always good for Cardinal tetras.

Some FAQs

Can You Put Two Heaters In Cardinal Tetras Tank?

You can, but the temperature will be a problem. Cardinal tetras need particular conditions. In my opinion, you should only have one heater in your Cardinal Tetra tank. It is because there are relatively higher chances of Cardinal Tetras dying from the clutches of a heater. Cardinal tetras are very sensitive to changes in water temperature, so they need gentle heating and not just any other kind of heating option.

Can Cardinal Tetras Live In A Heated Aquarium?

The short answer here would be yes! Although I have already mentioned that Cardinal Tetras need specific Cardinal Tetra tank conditions, it is not impossible to create them. Some people have reported Cardinal tetras living in heated aquariums. Still, their experiences are rare, and you should make your own judgment about the fish’s well-being when kept under high temperature all year round.

What Size Heater Do Cardinal Tetras Need?

Ideally, it would help if you got a 100W heater for your 20 gallon Cardinal Tetra aquarium because they are coldwater fish and need warmer water than room temperature. However, you could fit two 75 Watt heaters in there if you want to keep Cardinal Tetras in a bigger tank.

You Can Use A Heater For Cardinal Tetra Fish Tanks Or Not?

It is your preference if you feel like Cardinal tetras can live comfortably with less heat, but I am not sure of the fish’s well-being even though they are hardy and adaptable species. They may not die of cold water. But if the tank is too much hot, Cardinal tetras will undoubtedly suffer from several health problems.

What Temperature Should Cardinal Tetras Tank Be?

To ensure the Cardinal tetras tank is at the right temperature, you should check the aquarium thermometer regularly and maintain it between 72-78 degrees Fahrenheit. If the tank is at room temperature, you could consider using a heater to maintain the Cardinal Tetra’s preferred water temperature.


Cardinal tetras also tend to be more active and colorful when you keep them at higher temperatures. So, if you want to make sure your Cardinal Tetra is happy and healthy, it’s important to provide the best conditions possible for them.

Thank you for giving your time.

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