Cardinal Tetra: Profile, Behavior, Care, Size, pH, Breeding

Cardinal Tetra

The cardinal tetra, scientific name Paracheirodon axelrodi is a freshwater fish of the characin family (family Characidae) of the order Characiformes. It’s native to the upper Orinoco and Negro Rivers in South America.

The renowned American aquarium fish importer Herbert R. Axelrod made the first known observation of the cardinal tetra on a trip to South America in the 1930s. He made the decision to bring them back to the United States for aquarium aficionados after being moved by their magnificent color and tranquil demeanor.

The cardinal tetra quickly gained popularity and is currently among the most common species sold in aquariums. Unfortunately, unsustainable fishing methods have been used in some of the areas where cardinal tetras are native, which may have an effect on wild populations. It is crucial to only purchase cardinal tetras from reliable vendors and to select fish that have been ethically and sustainably raised in captivity.

Cardinal tetras are still found in their natural habitats all across the Amazon basin, despite the fact that they are now largely kept in home aquariums. In the environment, when the water is soft and acidic and the illumination is poor, they are generally discovered in flooded forests and slow-moving blackwater streams. They may be seen darting amid the foliage and leaf litter on the riverbank and are frequently encountered schooling with other tiny fish species.

Cardinal Tetra profile

In this article, I am going to talk about Cardinal Tetra vs neon tetra, profile, facts, description, care, tank mates, size, temperature, breeding, pH, water temperature, disease, etc.

Rising to about three cm (1.2 in) whole size, the cardinal tetra has the hanging iridescent blue line attribute of the genus Paracheirodon laterally bisecting the fish, with the body under this line being vivid red in coloration, therefore the identity “cardinal tetra”.

The cardinal tetra’s look is much like that of the carefully related neon tetra, with which it’s typically confused; the neon’s red coloration extends solely about halfway to the nostril, and the neon’s blue stripe is a less vibrant blue in color.

The cardinal tetra is a very popular aquarium fish, however, is less widespread than the neon tetra as a result till recently, it was difficult to breed in captivity.

Nevertheless, many breeders at the moment are producing the fish; most often one can decide if the cardinal tetra is bred or wild-caught attributable to damaged fins on wild-caught specimens.

Some ichthyologists believe fishkeepers ought to proceed to assist the sustainable cardinal fishery of the Amazon basin since thousands of people are employed within the area to capture fish for the aquarium trade.

If these fishermen misplaced their livelihoods catching cardinals and different tropical fish, they may flip their consideration to engaging in deforestation.


A little fish, the cardinal tetra normally reaches a length of 1.5 inches. Their striking coloring, which includes scales with iridescent blue and red pigment, is what makes them so well-liked among aquarium aficionados. The upper part of the fish is brilliant red, and the lower half is colored blue from the head to the belly. Just below their eyes, they also have a little blue patch that is iridescent.

The cardinal tetra is distinguished not just by its coloration but also by a characteristic black “line” that extends from its snout to its tail. This black line, commonly referred to as the “band,” aids in separating them from other tetra species that have a similar appearance.

Cardinal tetras have long, flowing fins that add to their beautiful look in addition to their vivid colors. Their anal fin, which is placed on the bottom of their body, is more rounded than their dorsal fin, which runs over the top of their body.

Cardinal tetra Description

The cardinal tetra has bright red ventral parts and an iridescent blue line that runs horizontally down the size of its body.

The attribute iridescence of this and associated fishes, such because the neon tetra, is a structural coloration, attributable to the refraction of light inside guanine crystals that develop inside particular cells referred to as iridocytes within the subcutaneous layer.

The precise shade of blue seen will depend on the viewing angle of the aquarist relative to the fish – if the aquarist changes viewpoint so as to look at the fish more from under, the color will change hue, changing into more deeply sapphire blue and even indigo.

Change the perspective to one above the fishes, nevertheless, and the color turns extra greenish.

Cardinal tetras seem to develop bigger in captivity than they do within the wild. They have a big abdomen and a small gut.


Cardinal tetras are discovered on the upper Orinoco and the Negro, which are situated in Colombia & Venezuela, and Brazil respectively.

Colors and Markings

The cardinal tetra has a superb neon blue stripe operating from the nose to the tail. Beneath this blue stripe is a superb red stripe.

The vivid red coloration bleeds into the tail, which is in any other case clear, as are the opposite fins. The underbelly is a soft white, setting off this fantastically colored fish.

A cardinal tetra could be distinguished from a neon tetra by the pink coloration band that extends the complete size of its body.

In the neon variety, the red band runs from solely the mid-body to the tail. Adults will show the most effective colors when supplied with very soft acidic water.

Typical Behavior

Cardinal Tetras are a colorful shoaling species that like to be kept in teams – the bigger the group the better (simply ensure the tank is big enough). They’ll swim collectively in the center and higher levels of the tank.

They’re much more confident when around others of their own type. If saved alone they might become pressured and shy, and in addition, lose some color.

They’re simply bullied by aggressive fish as they’re unable to defend themselves.

Like most Tetras, they’re peaceful and make a terrific addition to a community aquarium, however, they are often saved in a species-solely tank too.

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Tank Conditions

These fish don’t venture to the bottom of the aquarium fairly often, so you’ll be able to select any substrate.

In case you are starting a community with bottom-dwellers, a sandy substrate is greatest as a result of they’re less prone to scratch themselves.

You possibly can scatter around some decorations, however, plants are splendid in case you are trying to supply some shelter. Your Cardinal Tetras will disguise in them when stressed.

Anubias Nana, Amazon Swords, and Java Fern are some straightforward species to care for.

Just be sure you go away with loads of open water for swimming, as that is where your fish will spend most of their time together.

You should preserve appropriate water circumstances – hold the temperature between 73-81°F and the pH ought to be 6-7.

The filter outlet will create sufficient water motion and most traditional aquarium lights are fantastic.

Size of Aquarium

While Cardinal Tetras are small, they tend to reside in massive teams so you want a tank that may accommodate a group of at least six.

A 20-gallon aquarium will provide sufficient swimming houses to fulfill their energetic lifestyle.

Two gallons per additional Tetra is ok.

Cardinal tetra  Tankmates

Cardinal tetras, like different tetra species, are peaceful, social fish that ought to be saved in schools. Schools ought to be large, with a minimum measurement of a half-dozen fish.

They’re appropriate for community tanks so long as water conditions are favorable and different species are peaceful.

Potential tankmates that may be appropriate include different tetra species, danios, rasboras, dwarf gouramis, and small to medium members of the catfish family.

Don’t hold them with any fish that are identified to eat smaller, slim-bodied fish.

If the companion fish has a sufficiently big mouth to swallow the cardinal tetra, it isn’t a suitable tank mate.

Cardinal Tetra Habitat and Care

Very similar to the neon tetra, this species requires a mature tank that has soft acidic water.

More importantly, water chemistry should be secure. This isn’t a species that does well in a newly begun aquarium.

It is crucial to understand how to keep cardinal tetras healthy when it comes to its water requirements. The best pH is below 6, and the hardness shouldn’t be above 4 dGH. Subjecting this species to water that has excessive mineral content is a recipe for poor health and shortened lifespans.

The water temperature can encompass a broader range, from 73 to 81 degrees F (23 to 27 degrees C).

Lighting ought to be subdued as ought to the décor. Floating vegetation is a superb means for moderating the lighting.

Though they require some hiding areas, it is important to present them with some open water swimming space properly.

A well-planted tank with an open-heart house is a perfect habitat for this species.

Cardinal tetra Feeding

The cardinal tetra forages in areas of slow-moving shallow water. It’s predominantly predatory, usually feeding on tiny animals they discover on underwater vegetation, roots, and leaf litter.

Creatures generally eaten include the larvae of chironomid midges and microcrustaceans comparable to water fleas (Cladocera) of the families Moinidae, Macrotrichidae, and Daphniidae, and Copepods of the family Harpacticidae.

Different organisms eaten include different fly larvae, insect eggs, rotifers, and testate amoebae.

Parameters for water

Maintaining the right water conditions is crucial to the well-being of your cardinal tetras. They are used to soft, acidic water with a pH range of 4.0 to 7.0 in their native environment. Here are some crucial elements to take into account when trying to mimic these circumstances in your aquarium:

  • 72-82 degrees Fahrenheit, with 78 degrees being the optimal temperature
  • pH range: from 4.0 to 7.0.
  • Hardness: 1–10 dGH in the range. When the pH is within their optimal range, they may tolerate somewhat harsher water.

To keep the water in your tank in good condition, regular water changes are necessary. To maintain the water in your tank clean and conducive to the health of your fish, try to change 20 to 25 percent of it each week.

If you’re not sure about the quality of the water in your tank, think about utilizing a water testing kit to regularly check the pH, temperature, and other crucial characteristics.

Breeding and lifespan

The cardinal tetra, within the wild, swims upstream in massive numbers to components of its native river habitat fully enclosed above by rainforest cover.

Such waters are topic to heavy shading by the rainforest timber, and nearly no daylight reaches them. Here, the fishes spawn in massive aggregations.

Within the aquarium, a single pair could be conditioned for breeding, however, the breeding aquarium not solely must comprise water with the proper chemical parameters cited above, however, the breeding aquarium also must be closely shaded to imitate the low mild conditions of the fish’s native spawning grounds.

If the fishes are able to spawn, the male, which would be the slimmer of the 2 fishes in define, will pursue the feminine into fine-leaved vegetation; her fuller define, which normally signifies the presence of ripe eggs inside her reproductive tract, ought to be readily obvious at this level.

If the feminine is ready, she will allow the male to swim alongside her, and collectively, the pair will release eggs and sperm.

Parents have to be removed after the eggs and sperm are released, in any other case, they may eat the eggs.

The fish may also be successfully an annual species with a lifespan of only a single year in nature. It lives for a number of years in captivity.

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