Are Cardinal Tetras Hardy Fish: Shocking Truth

cardinal tetras hardy

Cardinal Tetras are such a joy to have in an aquarium. With glowing bodies and a friendly personality, it is no wonder why you and countless people are so captivated by this lovely Tetra. Not only that, but Cardinal Tetras are extremely hardy as well.

Cardinal Tetras are hardy fish and easily adapt to a wide range of water parameters. The fluctuation of temperature, pH, hardness, and so on are tolerated by this fish.

However, stress, unclean tank, and huge imbalance of water chemistry take a big toll on a Cardinal Tetras health. This is especially true for a new Tetra, juvenile, and tetra fry.

Why Are Cardinal Tetras Hardy?

Cardinal Tetras are hardy and adjust slowly (but surely) to changing water parameters that suit them. Due to this reason, Cardinal Tetras live to be about 5 years old in captivity!

Learn in detail about Cardinal Tetra (Paracheirodon axelrodi) from our Complete Care Guide.

Now, you may wonder why Cardinal Tetras are hardy. Let us find the reasons below.

Hardy Genes

This reason might be too obvious. Like, Cardinal Tetras are literally born hardy!

From Nature

Because Cardinal Tetras are low in demand, these fish are not so popular in your fish stores. Instead, most Cardinal Tetras are shipped from the wild.

Shipping from the wild means they are not bred (in-bred like Neon Tetras) to be sold in unethical ways. Thus, Cardinal Tetras are naturally healthy.

Find out more on Neon v/s Cardinal Tetra – The Difference.

Survival Of Fittest

Initially, the fish might have a hard time surviving in a pet store tank. Some even die due to parasitic diseases, stress, etc.

But, the ones who make it in your tank are the hardy ones. Do not be surprised if your Tetra survives to be 5 years old!

Get an idea about Tetra Fish Diseases and Treatments to be more careful about their health.

Wild Home Of Hardy Cardinal Tetras

In the wild, Cardinal Tetras are native to the upper Orinoco and Negro rivers in South Africa. These lovely Tetras are found in Colombia, Venezuela, and Brazil in abundance.

Cardinal Tetras are a fan of soft, acidic waters and generally reside in quiet banks and creeks. However, this fish can tolerate alkaline waters due to hardy nature.

Read more about how to Increase the pH of Your Freshwater Aquarium.

These lovely Tetras prefer a temperature of 71 degrees Fahrenheit or even warmer, up to 80 degrees Fahrenheit. Such a wide range, isn’t it?

The aquatic plants in freshwater balance the nitrogen cycle and wastes easily. Learn the top 10 aquarium plants for the tetra tank here.

Moreover, the decayed leaves produce tannins and make water dark (black water). This dark water is perfect for Cardinal Tetra. The cardinal Tetra can navigate the dark water with the glow from their body.

Find out more about what do Cardinal tetras eat.

Bring Amazon River Vibes For Your Hardy Cardinal Tetras Tank

Although hardy, Cardinal Tetras need care and love just like any other fish. Why not give your Cardinal Tetra a surprise by bringing tropical vibes in the tank?

I’m sure your Cardinal Tetra will thrive in the tank when you do this.

Big Tank For Hardy Cardinal Tetras

Tropical rivers are spacious. So, why not provide a big tank for your fish?

Find more on Are Tetra Tropical Fish? Tetra Origin and Habitat.

A 20-gallon tank that houses 10-12 Cardinal Tetras would be perfect for a beginner. I would suggest Tetra Aquarium 20 Gallon Fish Tank Kit, Includes LED Lighting and Decor.

Also, one important reminder: Cardinal Tetras are schooling fish and better paired in a group of 5 or more, i.e. 10-15 fish. Your aquarium will look pretty this way too.

A huge tank will give your fish a lot of space to swim in and it will make your fish very happy.

Learn about the Best Tank Size For Tetra Fish? Neon, Cardinal and Other Similar Tetras.

Maintain Water Parameters

Perhaps, maintaining water parameters is the most important thing while arranging a tank for your fish.

Water is where your fish basically lives, it is the essence of life. Thus, maintain clean water in your tank.


To maintain temperature, you have to buy a heater and thermometer.

For the water heater, you can use AQQA Mini Submersible Aquarium Heater while for the thermometer, the best one would be Fish Tank Thermometer, Touch Screen Digital Aquarium Thermometer with LCD Display, Stick-on Temperature Sensor ensures Optimum Temperature in Terrarium.

Then, maintain the temperature ranging from 74 to 80 degrees Fahrenheit with help of the heater.

With the thermometer, always check if the temperature is maintained.

In case of power shortage, arrange an inverter or generator, and maintain the temperature. Power shortage is fine as long as it lasts for a short time.

Learn more in our other article about how to Maintain Tetra Fish Tank Temperature Without Heater | Power Outage


You can maintain acidic water by keeping almond leaves or decayed leaves, peat moss, or driftwood. Then maintain the pH to 5.5 to 7. Your Cardinal Tetras will love it!

Is your Cardinal Tetra from the wild or captivity?

The wild ones can survive in varying pH (especially acidic) as the wild river has acidic pH from decayed leaves (tannins).

Take care about ones you brought from store tanks though. The store tanks mostly have neutral water. While providing acidic pH through Indian almond leaves, your store bred Cardinal Tetras might have a hard time.


Soft water with 5 dGH is ideal. But a range of 3-10 dGH would be good too.

The water in the tank should be free from minerals like magnesium, calcium, etc.

Hard water above 20 dGH can give hard time to your Cardinal Tetras. Below 15 dGH, your Tetra can adapt.

Nitrogen Level

Ammonia and nitrites only give disadvantages to your fish (burn of gills, bloating)!

Thus, to ensure that nitrogen levels do not spike in your tank, you have to check the ammonia level with a kit. The nitrogen level in your tank should be ideally 0 ppm (or <20 ppm).

Moreover, you have to clean your tank frequently. Especially after feeding time and after fish excretes wastes. How to Clean a Tetra Fish Tank? [Step-by-Step] and How often to clean a tetra tank? Find out here!

Replace the water every month, about 80% of it. Or else use the filter which is described below.

Moreover, a nitrogen cycle is necessary for good bacteria to develop. The good bacteria convert nitrogen into harmless material.


A filter ensures that any dirt is removed from your tank including fish wastes, excess food, chemicals, etc.

Moreover, a suitable clean environment is maintained favorable for your Cardinal Tetras.

Some filters are so powerful that you do not have to clean your tank for like 2-3 months. I would suggest Tetra Decorative ReptoFilter, Terrarium Filtration for your tetra tank.

Tank Mates

Cardinal Tetras are schooling fish and swim tightly in a group. Whenever a threat is around, Cardinal Tetras bunch up together in a shoal.

Thus, get as many Cardinal as you can. Buy in a group of 5 or more (10-20 fish) with a respectfully big tank!

Moreover, you can keep Cardinal Tetras with other friendly fish species as well. E.g. Glowlight Tetra, Neon Tetra, RCS shrimp, etc.

The rule of thumb is not to get a big fish whose mouth fits Cardinal Tetra. Because sooner or later, the big fish might eat your Cardinal.

Diet Of Hardy Cardinal Tetras

Cardinal Tetras are not fussy about food at all. Floating fish pellet or homemade food with necessary nutrients are good to go!

Feed your Tetra 1-2 times a day with long intervals in between.

At each feeding, feed only what your fish can consume under 2 minutes and not anymore.

Learn more on Tetra Fish Diet | What do Tetra Fish Eat: A Complete Guide.

Decoration, Lighting, And Plants

Cardinal Tetras are finicky and are easily scared. When Cardinal Tetras are scared, a safe hiding spot would make them feel better.

For this, you can buy driftwood, a castle, etc. Moreover, aquatic plants like Vallisneria, peat moss, pistia is perfect.

Decorations that cover up the entire aquarium can provide black water and a dark environment for your Tetras. Your fish will love it!

Dim lighting like LED suits Cardinal Tetras better rather than bright lighting.

Don’t Maintain Water Parameters And Tropical Vibes? Here’s What Will Happen!

If you do not maintain water parameters, your Tetra will have a hard time. See, Cardinal Tetras are hardy but that does not mean you neglect on caring for these lovely fish.

Here are some mistakes you might make:

Keeping Tetras in bulk before completing the nitrogen cycle is a common mistake you might make. The spike in nitrogen level can hurt your fish. Sometimes, even killing them.

Too many Cardinal Tetras in a small tank also stresses your fish. And stress lowers immunity which makes your fish prone to infection and parasites. Keep 10-12 Tetras in a 20-gallon tank and not anymore.

Hard water full of calcium and mineral deposits can give the disease to your fish too.

Moreover, an increase in temperature above 85 degrees Fahrenheit is a dire mistake. Your fish will dwindle and it might seem like your fish have died for no reason.

Even a cool temperature like 40-50 degrees Fahrenheit is dangerous. Your Tetra well tolerates a range of 70-80 degrees, but anything beyond the range of 70-80 degrees can lower the immunity of your fish.

Get deeper into Are Tetras Hardy Fish? – Different Parameter Levels.

Problems While Raising Hardy Cardinal Tetras

Although hardy, Cardinal Tetras may have a bad day. Let us find out some problems you may have while raising this lovely fish.

Look Out For Diseases

An imbalance of water parameters like too high temp, high or low pH, can lower your fish’s immunity. As a result, parasites can easily infect your fish. And your fish will die from diseases.

Some diseases like Neon Tetra disease is common in Cardinal Tetra.

Moreover, diseases like Ich is really common in Cardinal Tetras from the wild.

Get into details about Tetra Fish Diseases and Treatments.


Only recently have Cardinal Tetras been bred in captivity. This is because breeding Cardinal Tetras is a challenge!

Cannibalism is quite common in these fish. These fish lay eggs and eat their own baby.

Moreover, any uneven water parameter makes these fish infertile. So, there will be no babies at all.

Perhaps, you might maintain the water parameter and do everything right. But still, breeding is a huge hassle. You have to buy a separate tank, separate male from female, separate the adults right after they lay eggs, etc.

Learn more about Breeding Tetra Fish – Step By Step Guide.


Cardinal Tetras are hardy and take some time to adapt to a new environment. However, they do adapt pretty soon.

I hope you got to know how hardy Cardinal Tetras are and how you can provide a tropical freshwater vibe in your tank. Happy fish keeping!

Related articles:

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top