Cardinal Tetra Info and Care

The Neon Tetra may garner all the spotlight among freshwater fish but the Cardinal Tetra has almost all of the same qualities. The few ways in which it does differ actually make the Cardinal Tetra one of the most underrated fish in the freshwater hobby.

It is slightly more demanding and has a few characteristics that set it apart. As such, being able to keep them successfully boils down to having the correct care information for the Cardinal Tetra which is exactly what we will delve into now.

Cardinal Tetra Natural Habitat

The Cardinal Tetra originates from the river systems of South America such as the Rio Negro. It has also established viable populations in other regions of the Amazon thanks to either being released there or escaping from collectors. All these habitats share a few common aspects. The first is that these areas are all found in dense forests with a thick canopy that allows very little light to reach the water column.

The water itself is very clear but very soft and acidic. There are many places where the pH can drop to as low as 3.0. This is what makes them a bit more demanding compared to the other Tetras.

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Physical Description

The coloration of the Cardinal Tetra is very similar to that of the Neon Tetra and at first glance either can be misconstrued for the other. However, there are a few key differences. While the Neon Blue stripe runs all the way across the nose to the tail in both, it is the red stripe that makes the Cardinal Tetra different as the red stripe also runs across the full length of the body which is not the case with Neon Tetras. They also grow to be slightly larger at 2 inches. Apart from that, this fish has the same slender torpedo-shaped body.

Neon Tetra vs Cardinal Tetra

Cardinal TetraNeon Tetra
The red stripe runs all the way across the body The red stripe only runs halfway across the body from the nose
Grow to be 2″ inches in length, however, this difference isn’t as consistent as the difference in colorationStay smaller at a maximum length of about 1.5″

Cardinal Tetra Ideal Tank Setup

As mentioned previously, the Cardinal Tetra inhabits very slow-moving sheltered parts of the rivers of South America. Replicating these conditions is vital to their good health. Make sure that there is very little current inside the tank. A sandy substrate is a great option and the ideal setup would also have live plants as these fish love to hide among plants. Plants also make them exhibit their most brilliant coloration.

Another very important requirement is that the lighting has to be very subdued. This can be achieved in two ways. The first is by adding floating plants and using a low-wattage lighting system. The second is to add leaves and other substances that can leech tannins into the water. This second method will make the aquarium look dirty or more natural depending on how you look at it. Care must also be taken not to alter the water chemistry.

As these are highly social fish, they should be kept in relatively large groups, and as such a 20-gallon tank is the minimum recommended size for these fish.

Water Parameters

This is where a lot of misconception exists and consequently why hobbyists find less success with the Cardinal Tetra as opposed to other tetras. The pH requirement of this fish sets it apart. They prefer pretty acidic water and the pH should not rise above 6.0. The hardness should not exceed 4 dGH and the water used should be low in minerals or else their health will be impacted negatively.

The temperature should be maintained between 73°F and 81°F or 23°C and 27°C. Finally, make sure that the tank is properly cycled and mature.

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Feeding Cardinal Tetras

These fish are omnivores and will readily accept commercially available fish food. They do require a good amount of micronutrients such as vitamins and as such you should choose a food that is of high quality and preferable meant for Neon and Cardinal Tetras. They do love live and frozen food but these should only be used as the occasional treat. Regularly feeding live and frozen food will cause Cardinal Tetras to totally avoid flakes and pellets.

Cardinal Tetra Behavior And Tank Mates

The Cardinal Tetra like most of its cousins is a docile and peaceful fish. As alluded to earlier, they should be kept in schools preferably of six or their own kind. They do well in community tanks as long as their tankmates are peaceful as well and do not grow to be too big.

Ideal tankmates for the Cardinal Tetra include:

Avoid any fish that has a mouth large enough to fit the Cardinal Tetra

Breeding Cardinal Tetras

Breeding Cardinal Tetras

These fish are among the hardest to sex as the males and females are nearly identical. However, keeping them in a large enough group will ensure that there is a healthy mix of both genders. Breeding Cardinal Tetras is one of the most difficult tasks in the freshwater hobby.

Ideally, it should be left to the pros but if you really want to try your hand at breeding these beautiful fish then start by preparing a breeding tank. It should have soft and acidic water that is 3dCH or lower with a pH of 5.0. The tank should have very subdued lighting.

Add a dozen or so Cardinal Tetras and wait for them to spawn. This will usually happen in the evening or the night and anywhere between 100 and 500 eggs will be laid.

Turn the lights off completely at this point as the fry are highly photosensitive. They should hatch in about 24 hours and will subsist on their yolk sac for the first 3-4 days. After this feed them the smallest fry food you can find followed by freshly hatched brine shrimp after a couple of weeks. It will take these fry about 8-10 weeks to achieve adult coloration.


The Cardinal Tetra is one of those species that is naturally very resistant to diseases. However, they are incredibly sensitive to water conditions and even the smallest amount of instability will lead to major health issues. Thankfully, they will start to lose their coloration if something is wrong and this can act as an early warning system provided you find out what is wrong and fix it quickly.

As long as the aforementioned water parameters are maintained without any compromises and a strict maintenance regimen is followed with weekly water changes, Cardinal Tetras should thrive and live to their maximum lifespan of about 5 years.

To Sum It Up!

The Cardinal Tetra may be slightly more demanding than most Tetras but it is worth the added effort. It is prettier than the Neon Tetra and more rarefied and if you want to graduate to something small but challenging and you want an explosion of color in your aquarium then the Cardinal Tetra is the perfect fish for you.

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Cardinal Tetra Care and Info
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