Cardinal Tetra (Paracheirodon axelrodi) – Delicate Beauties

The Cardinal Tetra (Paracheirodon axelrodi) is a spectacular delicate beauty that has been described as “one of the most popular aquarium fish ever”  by many tropical fish keeping enthusiasts.

The Cardinal Tetra (Paracheirodon axelrodi) like it’s peaceful cousin the Neon Tetra is a charming little schooling fish that is in both appearance and behavior awesome. Although it is slightly more delicate than the Neon Tetra, it thrives in large schools with it’s own kind and should be housed in densely planted, dimly lit aquariums of at least 15 gallons. The larger the aquarium, the easier they are to take care of and the healthier they stay.

Cardinal Tetra (Paracheirodon axelrodi)

Cardinal Tetra (Paracheirodon axelrodi)

The Cardinal Tetra (Paracheirodon axelrodi) has a distinctive color pattern with a brilliant neon blue stripe above it’s center line and a bright (Cardinal) red stripe extending through its entire body length below. It is often referred to as the “big brother” of the Neon Tetra and the two color patterns are similar. The difference is that the Cardinal Tetra has the red coloration extending through it’s entire body length and in the Neon, the red is limited to the back half of the fish.

The brilliant contrast of the Cardinal Tetra’s colors is startling when viewed in low light conditions and their colors improve when they are housed together in large schools. The bigger the school; the more radiant their coloration becomes.

Plant their tank heavily with shrimp pellets, water sprite, etc. in a dark substrate, provide them with a lot of swimming space, some driftwood (bogwood) to hide in, keep their water soft, the pH acidic, and their colors become even brighter.

Cardinal Tetras cannot tolerate harsh light conditions, so don’t leave the hood lights on without providing them with some places to hide.

In the vegetated slow moving tributaries of South America where they were originally collected, Cardinal Tetras travel in huge shoals and live in very low light conditions under the rainforest canopy.

This is why they should be kept in groups of 10 or more with other equally peaceful tank mates like pencil fish, hatchet fish, small rasboras, dwarf cichlids, small Loricariids, and anabantoids.

Although native to the upper Orinoco and Negro Rivers, like the Neon Tetra they are being bred in captivity for the aquarium trade.

Breeding the Cardinal Tetra is similar to breeding Neon Tetras.  You need to provide the adults with soft water in the 1-2 dH range, a pH of 5-6, a temperature of 82 degrees F. and low lighting.   Female Cardinal Tetras will lay as many as 180 eggs at which time the parents should be taken from the tank.  The eggs are photosensitive and will die if exposed to bright light.  Consequently, after spawning, the aquarium should be covered to darken it and provide the developing eggs the conditions necessary for a successful hatch.

At 82 degrees F.  the eggs will normally hatch in as little as 24 hours, to as long as  3 days .  The fry remain waterborne and photosensitive for approximately 5 – 7  days.  During this period gradually increase the light in the tank.  The The fry should be fed newly hatched baby brine shrimp or water Daphnia after their egg sacs are absorbed.  After 8 to 12 weeks the fry reach adulthood and full coloration .

When Cardinals are kept in favorable conditions, they are easy to keep and resist diseases. However, when housed in unstable conditions they quickly decline in color quality and will die.   Neon Tetra disease is a primary concern for tropical fish keeping enthusiasts who keep Cardinal and Neon Tetras.   It affects many species of fish, is highly contagious and to date is incurable.

When purchasing Cardinal Tetras, look for commercially bred specimens with good color and that are in good condition.    Whenever possible,  purchase larger specimens, especially if they have been caught in the wild.

The wild caught specimens have more vibrant colors than commercially bred fish but are not as tolerant to unstable water conditions that inevitably occur in freshwater aquariums.

When available for purchase, Cardinal Tetras are usually 3/4″ to 1-1/2″ in size.


Cardinal Tetra (Paracheirodon axelrodi)

Cardinal Tetra (Paracheirodon axelrodi)








Minimum Tank Size: 15 gallons
Care Level: Moderate
Temperament: Peaceful
Aquarium Hardiness: Less hardy than Neon Tetras
Water Conditions: 73-81° F, KH 2-6, pH 5.5-7.5
Max. Size: 3″
Color Form: Iridescent Blue, Red
Diet: Omnivore
Compatibility: Peaceful, keep with other small tetras
Origin: Farm Raised in Europe, Indigenous to South America
Family: Characidae
Lifespan: Up to 8 years
Aquarist Experience Level: Moderate Experience

3 Responses to “Cardinal Tetra (Paracheirodon axelrodi) – Delicate Beauties”


  1. […] are quite peaceful and can be kept with other peaceful, heat-loving species, such as cardinal tetras, clown loaches and rasboras. They should not be kept with angelfish which are prone to parasitic […]

  2. […]   As a community fish, they can be housed with any similar sized, non aggressive species such as Cardinal Tetras, Corydoras, Glowlight Rasboras, Dwarf Gouramis, Otocinclus Catfish, Threelined Pencilfish, […]

  3. […] of the Rio Negro in the Amazonas state of Brazil.   Their range coincides with that of the Cardinal Tetra (Paracheirodon axelrodi) but the two species are not found […]

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