Cardinal Tetra Complete Care Guide

Cardinal tetras are the perfect beginner fish.

They are hardy, easy to care for, and very colorful.

A group of them is great for showing off their vibrant colors, and their synchronized movements are almost hypnotic.

Cardinal Tetras are being bred more and more, they are now a common sight in community fish tanks.

If you want to keep these fish, you will need to know their ideal environment, diet, and tank mates. We will cover all of this and much more in this article…

See also: kissing gourami

Cardinal Tetra Facts & Overview

Cardinal Tetra Appearance

Care Level:Easy
Color:Blue and red
Lifespan:Up to 5 years
Size:Up to 2 inches
Minimum Tank Size:20 gallons
Tank Setup:Tropical freshwater with open swimming space
Compatibility:Peaceful community

The Cardinal Tetra (Paracheirodon axelrodi) is a social fish from the Characidae family. They are sometimes referred to as Red Neon Tetra due to their similarity to the famous neon tetra.

Cardinal Tetras are growing in popularity and can be found in most pet stores for as little as $2.

These fish are native to the Orinoco and Negro Rivers in South America. This continent is home to many species of Tetra, though some are found in Africa and Central America.

They are easy to incorporate into a community aquarium.

Even beginners can enjoy the color and activity they bring with them because they are hardy and enjoy a range of conditions.

In a clean tank, they can live for up to five years.

Typical Behavior

Cardinal Tetras are a colorful shoaling species that love to be kept in groups – the larger the group the better (just make sure the tank is big enough). They will swim together in the middle and upper levels of the tank.

They are much more confident when around others of their own kind. If kept alone they would become stressed and shy, and also lose some color. They are easily bullied by aggressive fish as they are unable to defend themselves.

Like most Tetras, they are peaceful and make a great addition to a community aquarium, but they can be kept in a species-only tank too.


Cardinal Tetra Care

This small fish only reaches 2 inches long.

The main attraction of Cardinal Tetras is their color. Their fins are small and don’t grab your attention.

Their bodies are typically red and blue. A red stripe runs along the lower side from head to tail, a blue stripe sits just on top. The colors are bright, so a shoal can be a striking sight.

Evidence suggests that these species can change their colors too.

Whilst red and blue is the most popular color, you can find them in golds and silvers (these are much less common).

It is very difficult to identify the males from the females because they have the same coloration. You can spot females if they are carrying eggs because they will have a rounded body.

You do not usually need to sex this species since they are kept in large groups, so you will likely have a good mix of males and females.

Cardinal Tetra vs Neon Tetra

These fish are often confused with Neon Tetras as they have the same coloration.

The main difference is a Neon Tetra’s red stripe only runs halfway up their body, and their blue stripe is a less vibrant blue.

Habitat and Tank Requirements

Cardinal Tetra Overview

Cardinal Tetras naturally live in flooded forest areas, shallow creeks and tributaries to large rivers in South America.

Although there are plants and rocks spread around the bottom of the water column, there is lots of open space for swimming.

The environment would be warm and slightly acidic and the shallow waters move slowly. Some areas receive lots of sunlight, and others are heavily shaded.

Understanding a fish’s natural habitat is great for helping you set up the perfect tank for them.

Tank Conditions

These fish don’t venture to the bottom of the aquarium very often, so you can choose any substrate. If you are starting a community with bottom-dwellers, a sandy substrate is best because they are less likely to scratch themselves.

You can scatter around some decorations, but plants are ideal if you are trying to provide some shelter. Your Cardinal Tetras will hide in them when stressed.

Anubias Nana, Amazon Swords, and Java fern are some easy species to care for.

Make sure that you leave plenty of open water for swimming, as this is where your fish will spend most of their time together.

You need to maintain suitable water conditions – keep the temperature between 73-81°F and the pH should be 6-7. The filter outlet will create enough water movement and most standard aquarium lights are fine.

What Size Aquarium Do Cardinal Tetras Need?

Whilst Cardinal Tetras are small, they tend to live in large groups so you need a tank that can accommodate a group of at least six.

A 20-gallon aquarium will provide enough swimming space to meet their active lifestyle.

Two gallons per additional Tetra is fine.

Tank Mates

Cardinal Tetra Tank Mates

This peaceful species is suitable for community aquariums.

They stick to their own shoals and will generally ignore anything else in the tank. Therefore, they can be kept with most other peaceful fish.

Aggressive or territorial species will bully your Cardinal Tetra, stressing them out to the point of death – one example of this is the Rainbow Shark.

Large fish should be avoided too as Cardinal Tetra are small and easily eaten by those with large mouths.

Some good tank mates include Neon Tetras, zebra danios, hatchetfish, mollies, dwarf gourami, angelfish, and guppies.

Zebra Loaches, yoyo loaches, and Otocinclus work well if you are looking for occupants in the lower regions of your tank.

Cherry shrimp and mystery snails are also compatible and are a great way to diversify the behaviors in your tank.

See also: Red Arowana

Keeping Cardinal Tetra Together

You should definitely be keeping Cardinal Tetra in groups. They need to be in shoals of at least six to bring out their natural behaviors.

The bigger the shoal, the happier they will be.


Cardinal Tetra Habitat

Cardinal Tetra are omnivorous, and will eat virtually anything you put into your tank.

There are many types of fish food available, and each has their pros and cons.

Generally it is best to mix a few types into a fish’s diet to make sure they are receiving a balanced diet.

Dried foods are the easiest to get your hands on. They are the most commonly sold and usually the cheapest. However, for that convenience you sacrifice most of the nutritional content. There are far fewer nutrients in dried foods compared to live or frozen foods.

Live and frozen foods are full of nutrients, so you should use them to supplement the rest of their diet. You can also add green vegetables to the tank. This varies the diet and helps to prevent food waste. Chop them up and only give them small amounts.

Feed adults twice a day, giving them what they can easily finish in two minutes. If any food is left over, remove it before it breaks down in the water.


The Cardinal Tetra is an easy fish to care for.

They are fairly undemanding and can tolerate a range of water conditions and setups. However, they can get ill just like all aquarium fish.

One of the most important parts of caring for them is choosing the right diet. If your Cardinal Tetras are not receiving the nutrients they need, then they will lose their color and their immune systems will weaken.

Another thing that can weaken the immune system is a sudden change in environmental conditions. For example, these fish cannot survive a drop of temperature for long.

Not only do parameters need to remain stable, but the aquarium should be kept clean. Regular water changes prevent the buildup of pollutants. You should also wipe down excess algae before it can cause issues.

One disease to look out for in your tank is Neon Tetra Disease, which affects many species of Tetra. It is caused by a parasite and leads to symptoms such as a loss of color, cysts, a curved spinal, and secondary infections.

It usually enters the tank when adding un-quarantined fish or feeding with infected live foods. There is no known cure for this disease, most infected fish are euthanized. Remove them from the tank as quickly as possible so that they are not eaten and don’t infect other fish.

Other diseases that you might experience are fin rot, ich, and bloat. These are more well-known and much easier to treat.


Cardinal Tetras will naturally breed upstream in shaded regions.

The good news is they can be bred at home, they just need quality conditions which replicate their natural breeding environment.

Start by switching off aquarium lights.

You need to stay on top of cleaning your tank, weekly water changes are important for this. Parameters must remain stable and you cannot let pollutants or algae build up.

A nutritional diet is also important for getting your fish ready to mate. A female will have a more rounded body when she’s ready because she will be carrying eggs. She will let a male swim alongside her as they move around plants. They will then release the sperm and eggs.

Eggs should hatch after three days.

The fry will be too small to eat an adult diet, so feed them tiny foods like infusoria until they are big enough. The young will be photosensitive once hatched, so gradually raise the light intensity back to normal conditions.

After 8-12 weeks, they should have the colors to match the adults.

Is the Cardinal Tetra Right For Your Aquarium?

Beginners will feel very comfortable with Cardinal Tetra.

They are hardy and peaceful, so they can be kept in a range of tropical setups. They are undemanding fish which makes it simple to design a suitable tank. Feeding them is just as simple, and you could even try to breed them.

A shoaling species like this is a very attractive option for your aquarium. You will love to watch them move around the tank in unison, showing off their bright colors as they swim.

Are Cardinal Tetras your favorite shoaling fish? Let us know in the comments section below…

About Robert 386 Articles
Robert Woods is the creator of FishKeeping World, a third-generation fish keeper, and a graduate in animal welfare and behavior. He is also a proud member of the Association of Zoos and Aquariums, the Marine Aquarium Societies of North America, and the Nature Conservancy.


  1. Sunil says:

    Excellent information

  2. Rob says:

    Angelfish can and will eat smaller cardinals..

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