What You Should Know Before Adding a Cardinal Tetra to Your Aquarium

Cardinal tetras, also known as Red Neon tetras are a very popular choice for standard in-home aquariums. Similar to the standard Neon tetra fan favorite, the Cardinal tetra is very similar but is also easily recognizable by the wide and bright red coloring of the lower half of its body.

Boasting the scientific name Paracheirodon axelrodi these tetras are very pleasant to look at and moderately easy to look after. If this is your first time setting up an aquarium, however, you will need to do quite a bit of research and preparation. That’s true regardless of what fish you’re going to look after – there’s just some know-how that needs to be acquired.

So, what do you need to prepare for your Cardinal tetra? Below are the 20 things to know before getting a Cardinal tetra into your aquarium.

1. Are Cardinal Tetras good for beginners?

Overall, Cardinal tetras are pretty good for beginners. In fact, many would say that they are the perfect fish for beginners, although we’d point out that they are tricky to breed (more on that below). However, if you don’t intend to breed your tetras, then – yes, these tiny fish are great for beginners.

2. Is the Cardinal Tetra high maintenance or low maintenance?

The Cardinal tetra is pretty low maintenance. Their aquarium is easy to set up, their water condition needs are easy to manage (more below), and they are pretty easy to feed. The only complicated thing is that they need to be fed 2-4 times a day every day. So, when you want to travel you’ll need someone to take care of your fish pretty diligently.

3. Are Cardinal Tetras rare in pet stores?

The Cardinal tetra has been difficult to breed in captivity for quite some time which is why neon tetras are much more common. Still, Cardinal tetras aren’t “rare” either and can be found pretty easily in most pet stores that sell aquarium fish. They aren’t too pricey either – most stores will sell Cardinal tetras for about $3-4 apiece.

4. How big are Cardinal Tetras?

The average adult Cardinal tetra will grow to about 2 inches or 5 cm. This small size is a big reason why these fish are so popular and easily looked after in residential aquariums. If your tetras don’t grow to that size, however, and stay smaller, it may be wise to consult with a veterinarian or a fish expert. Likely causes of the problem include imperfect water conditions, insufficient or inadequate food, and/or stress.

5. How long does a Cardinal Tetra live?

The expected lifespan of Cardinal tetras in captivity is about 4 years. Longer than that is possible but rare even with the right conditions. However, if most of your fish are passing away sooner than that, something may be wrong. As with above, the key problems to look at first are the water quality, food, and stress.

6. How many Cardinal Tetras should be kept together?

The very minimum you should get is half a dozen tetras for a proper “school” of fish. These are social fish so they need at least as many friends to keep them company. As for a maximum number – the more the merrier, as long as your aquarium is large enough.

Most experts recommend up to 8 tetras in a 10-gallon tank and up to 15 in a 40-gallon tank. However, others maintain that you can put s many as 3-4 tetras per gallon of water. Still, we tend to agree with the former as overcrowding seems to lead to health problems and deaths for Cardinal tetras.

7. Can Cardinal Tetras breed in captivity?

They can but it’s a pretty tall order. You’ll need a separate breeding tank with perfect water conditions. There, the tetras will spawn between 130 and 500 eggs in the dead of night. The eggs will start hatching in about 24 hours and will live off the yolk sac for 4-5 more days.

You should start feeding the newborn fish rotifers, infusoria, egg yolk, and commercially prepared fry food as soon as they start swimming freely. Then move on to freshly hatched brine shrimp as the tetras grow. Keep lighting low as young tetras are very photo-sensitive.

8. Do Cardinal Tetras breed easily?

Not really. While adults can be taken care of easily, young tetras are hard to raise and keep alive.

9. How big should a Cardinal Tetra aquarium be?

A Cardinal tetra aquarium can be as big as you want it to be but 10 gallons is recommended as a bare minimum as you want to have at least 6-8 tetras grouped together. As for an upper limit – there is none, go for as big as you want.

10. What are the gender differences between male and female Cardinal tetras?

Female tetras have “deeper” bodies with more rounded bellies. Males tend to be more slender and have a hook coming out of their anal fin.

11. Can Tetras live with Angelfish?

Indeed they can. As a matter of fact, angelfish share a habitat in the Amazon River Basin with Head and Tail Light tetras so they definitely don’t mind sharing an aquarium together either.

12. Will Cardinal Tetras school with Neon Tetras?

Both types of tetras school very well together. In fact, the same goes for all types of tetras – these fish are just that social!

13. What other fish can the Cardinal tetra be housed together with?

All tetras get along and can also live with many other fish, as long as they all share the same environmental needs. Other common and suitable tankmates for the Cardinal tetra in addition to the Angelfish include Dwarf Gouramis, Kuhli Loach, Rasboras, Cherry shrimps, Bristlenose, Danios, Corydoras, and many small-to-medium-sized Catfish species.

As for undesirable tankmates – this includes every fish that’s big enough to eat a Cardinal tetra as well as any fish that doesn’t share the tetra’s environmental requirements. Here’s an awesome video on the different types of fish you can house with a Cardinal tetra.

14. What should you feed a Cardinal Tetra?

Tetras are omnivores and can eat almost anything. The ideal diet, however, should include 75% high-quality pet store flake food because these fish have high vitamin needs. The rest can be any type of live, frozen, or prepared food.

15. How often should you feed Cardinal Tetras?

Cardinal tetras should be fed a minimum of two times a day – more if possible. If you only feed your fish twice a day, give them as much as they can eat in 5 minutes. If you feed them 3-4 times a day, give them as much as they can eat in 2.5-3 minutes per feeding. Don’t overfeed them, however – they will either start getting sickly or the aquarium water will get dirty. Here’sa neat video of feeding Cardinal tetras.

16. Why do my Cardinal Tetras keep dying?

There can be many reasons why your tetras don’t stick around. The most likely culprits include bad water conditions, rapid water changes, an overcrowded aquarium, overfeeding, stress, as well as diseases. If you suspect the latter, look for symptoms such as restlessness, difficulties swimming, cysts and lumps on the body, a loss of coloration, and a curved spine.

17. What water temperature do Cardinal Tetras like?

The ideal temperature range for Cardinal tetras is 73 to 81 degrees Fahrenheit (23 to 27 degrees C). Fortunately, this is in line with the temperature preferences of quite a few other common aquarium fish species.

18. What’s the right water pH for Cardinal Tetras?

4.5 to 6.2 pH is the adequate pH range for Cardinal tetras. Anything below or above that will be detrimental to your tropical fish’s health. In the wild, the standard pH level these fish live in is about 5 pH.

19. What water hardness does a Cardinal Tetra school need?

The ideal water hardness for Cardinal tetras is anywhere up to 4 dGH. This is quite soft but that’s what this fish’s natural waters in the Amazon are like.

20. Is the Cardinal Tetra endangered?

This tiny fish is native to Brazil, Columbia, and Venezuela where it lives in the fresh waters of River Orinoco, Rio Negro, and other tributary rivers of the Amazon. While the species itself isn’t endangered, its environment is “under fire” as of late – literally . So, getting Cardinal tetras for your aquarium won’t really put these fish at risk of going extinct. Instead, if that happens, it will be because the Brazilian Amazon forests aren’t being helped in any way.

As you can see, Cardinal tetras are a pretty great choice for any aquarium, even if you’re a beginner. Admittedly, they are a little difficult to breed, but as long as you take care of everything else, you should have the opportunity to get the hang of that too.