Cardinal Tetra vs Neon Tetra: What’s the Difference?

Cardinal Tetra

Of all the Tetras, there are two which are the most popular, and that are in the most demand. They are the Cardinal Tetra (Paracheirodon axelrodi) and the Neon Tetra (Paracheirodon innuesi). They are sparkling, colorful, adorable fish! Have you found yourself trying to choose between the two, like some of my clients?

What is the difference between Cardinal Tetra and Neon Tetra? Cardinals have red stripes on the lower half of their body, running from their eye to their tails. For Neon Tetras, however, the red does not run all the way to the head of the fish—it stops halfway from the tail. The remaining part is covered with blue. Most people find the Neon’s cluster of colors less appealing than the Cardinal’s.

Even though they share a lot of similarities, in fact they are very different, and when you get to understand the differences, you will realize that they are actually very easy to differentiate. There are differences in their appearance, and they also require different environmental conditions. 

They have different natural habitats, prefer different water conditions, and feed on different food. We will detail all this below.

In truth, the Tetra is a fantastic fish pet—they can brighten your tank the same way stars and fireworks brighten the night sky, and the morning sun brightens the day.

Do you already have a tank, and just want to add a Tetra, but don’t know which one to choose? Or are you in the process of getting a tank and keen to know the right set up for breeding Tetras?

This article will tell you everything you need to know about these fish, and will help you to decide which Tetra to buy when you next go fish shopping!

You probably have lots of questions – but don’t worry, as I expect my clients have already asked them all, and I will list all the answers in this article.

Do these Tetras have the same origin?

Yes, you could say that. The two fish can both be found in South America, they also can both be found in Brazil. The Cardinal Tetra tends to be found in the north and the Neon Tetra can be found in other parts of Brazil.

Cardinals are particularly found in the Orinoco and in some parts of Columbia. Neons are found in Singapore, Thailand, Hong Kong and like I said, Brazil.

So, if you are planning on visiting any of these places soon, make sure to ask the locals about these fish. However, it should be noted that these two breeds of Tetra are never found together. So although it’s true to say they are both from South America, they do not inhabit the same territories, so have different origins.

Can Cardinal Tetra live with Neon Tetra?

This is a particularly good question, because even after I have explained the differences between the two tetras to my clients, they are still not sure whether the two can live together in the same tank. In theory yes, they can live together, as they are not enemies. But it’s unlikely to be a good pairing for reasons that I am about to go into.

Cardinal Tetra

Will Cardinal Tetra school with Neon Tetra?

When aquarists use the term schooling, they are referring to how fish relate together in groups. Tetra fish are mostly schooling fish. They appreciate having a good number of others like them around.

Actually, they ‘follow the crowd’. If one turns right, the others immediately turn that way and you will find them all going in the same direction. They move together and share confidence in one another.

That’s why if you have only one member of the Tetra family in your aquarium, it won’t last more than a few days. But will a Cardinal Tetra school with a Neon or vice versa, since they are both Tetras? It’s like expecting a dog and a rat to get married because they are mammals, make sense? Hell no, Cardinal and Neon Tetra can’t school together.

Can all Tetra fishes together?

This is another good question, without a simple answer. Bringing a group of animals together because they belong to the same family isn’t a bad idea. But while some Tetra prefer a temperature of no more than 70°F, others can go as high as 82°F.

Neon Tetras, for instance, prefer a low light environment with plenty of overgrown plants, driftwood, and rocks where they can easily hide.

Cardinals instead prefer plants that are not overgrown, and actually prefer floating plants. Some prefer 6.0-6.5 pH whereas others prefer a much lower pH. So when you are putting your tank together, it’s almost impossible to balance all these varying needs. For this reason, I’d tell you not to try mixing different breeds of Tetra fish together. More reasons why it’s not a good idea are listed below.

More: How Many Tetras in a 5 Gallon Tank?

Cardinal Tetra Vs Neon Tetra – Size

My clients are not always concerned about the size of their fish, but it is actually the easiest way to differentiate the Cardinal and the Neon from a distance. Really? Trust me, I’ll explain shortly.

Neon Tetra Vs Cardinal Tetra -Care

This is important! You need to know how much you might be spending on each of these fish, and how hard they are to look after, before deciding on which one to buy. Beginning with cost, Cardinals are more expensive, but also more reliable.

Differences Between Neon Tetra and Cardinal Tetra

Firstly, the two fish obviously have very similar characteristics, and this is why aquarium lovers have problems recognizing and choosing between them.

Here are the similarities between Neon and Cardinal Tetra:

  • They are both members of the Tetra family, originating in South America.
  • They are both wild animals that can be found in rivers and lakes.
  • They both can be found in captivity too, although the Neon is mostly found in captivity.
  • In captivity, you can feed them both with the same food.
  • Their colors and outer appearance are similar.
  • They both enjoy acidic water, though to different degrees.
  • They are both pet fish that enjoy schooling, meaning that if you want one to stay alive, then you’ve got to keep at least five others as they need a minimum of 6 fish in their schools. This applies to both Cardinals and Neons.

But telling them apart is SIMPLE! You just need to look at their colors. 

Neon Tetra

So, if you find the two breeds in a tank, you can easily differentiate them. Even when it’s just one breed, remember the color difference and you can easily recognize it.

Length is another trait you can use to differentiate them from afar. If the Tetra you are looking at is more than one inch long, it’s definitely not a Neon.

No matter how old a Neon Tetra gets, it will not grow longer than 1.2 inches. So if your fish is longer than about 1.5 to 2 inches, you can easily tell which fish it is.

The problem is: when a Cardinal Tetra is growing, it may be the same length as a Neon. But not to worry, you can always rely on their other differences to tell them apart.

What do they eat?

One another difference between them is the type of food they eat, since Cardinal Tetras are mostly wild and found in areas where slow and very tiny objects live. They mostly feed on tiny worms, crustaceans, detritus and algae.

Neon Tetras instead prefer to eat larger food such as worms, bugs and some varieties of plants. Interestingly, the bigger Tetra feeds on the smaller animals.

But this is just what happens in the wild. If you have them both in your tank and you need to feed them, you can feed them both on shrimp, daphnia and flakes.

They may not be used to it at first, but they will quickly adapt as they follow the crowd. It just takes one of them to pick it up accidentally, and soon they will all be feeding on it. You can feed them on tubifex worms and brine too.

Can you rear the two Tetras together?

The environment is the biggest issue with raising Cardinals and Neons together. Many of my clients wonder if there’s a way to rear the two breeds together.

In the wild, Cardinals prefer to live in streams, ponds and non-flowing water bodies. Neon Tetras prefer the bigger water bodies such as lakes.

So as you will see, these fish have different habitat preferences. Neon Tetras also enjoy fairly acidic water (say 6.0 pH to 6.8 pH), whereas Cardinal Tetras need a pH between 4.5-6.2.

In theory, both fish can survive in about 5.8-6.2 pH, but it’s a 50-50 chance as they may both find it uncomfortable; too low for Neon Tetras and too high for Cardinals.

The maximum water level hardness any aquarist would ever want to use for Cardinals is 5 while Neon Tetras prefer it to be higher. Neon Tetras would also rather inhabit cool water, while Cardinal Tetras prefer it to be warmer.

Whichever way you play it, you may be lucky enough to have both breeds survive. Many people believe that Cardinal Tetras are stronger, healthier fish, but there is actually no scientific evidence to prove this. There have been a few repots – such as Bernadette and Co. who discovered in 2002 that Columnaris Bacteria affected a bunch of Neon Tetras farmed in France. Aquarists also say Neon Tetras die too easily. No such report was ever given on Cardinals.

More: Best Fish for 5 Gallon Tank

This is probably because they are so wild, and almost nobody rears them, so we don’t really know what affects them and what doesn’t. However, we do know that, unlike their cousins, the Cardinals find it really difficult to adjust to water reactions and are very sensitive to changes, and this should be taken into consideration when choosing your Tetras.

The care of the Tetras

This is probably the most important thing to consider when choosing which Tetra to buy. Most Neon Tetras love dark spots, so I’d really recommend that you get yourself some driftwood that contains Tannins.

Remember tannins are released by driftwood into the water, turning it black but not harming the fish. If you don’t want a dark aquarium, then I wouldn’t recommend Neon Tetras!

However, if you DO like a dark tank, then Neons should be your first choice. They like to hide and love having lots of plants, so make sure that you provide ample plants in the tank and build an underwater forest.

Chola wood is a good choice.

Cardinals? All they want is non-moving water, with fewer plants and ample space for them to spread out and swim and play. You should let them have fun with driftwood too, but not much. They also don’t like excess light, but they prefer clearer water.

Now that you know the differences and similarities between a Cardinal Tetra and Neon Tetra, which one will you choose? Tell me below.

Saurabh Kumar

I am a passionate fish keeper, with years of experience. You will find some really useful tips and information on this blog about Freshwater Aquariums.

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