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Encyclopedia / Tetras / Cardinal tetra
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Variations

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Cardinal tetra

Paracheirodon axelrodi · Cardinal

Like a neon, but the red runs the full length of the body. Prefers warmer, softer water.

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3 cmBody length, without tail ✓
23–29 °CTemperature ✓
4.5–7pH ✓
54 LSmallest tank ✓
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Tank mates
Check your own mix →
Not recommended
  • Tinfoil barb eats animals up to about 5 cm. Cardinal tetra only grows to 3 cm.
Not recommended
  • White cloud mountain minnow needs cool water and makes a lot of waste, while Cardinal tetra is tropical.
  • They need different temperatures (23–29 °C vs 14–22 °C). No setting suits both.
Not recommended
  • Pearl gourami eats animals up to about 3 cm. Cardinal tetra only grows to 3 cm.
With conditions
  • Only a narrow temperature range suits both: 23–24 °C.
With conditions
  • Only a narrow temperature range suits both: 23–24 °C.
Compatible
Compatible
Compatible
Compatible
Compatible

284 species in our list are a good match.

Facts checked against sources on 16 Oct 2026. ✓ means a source backs it; ? means no reliable source yet. See sources

Care and water

Hardness ✓1–8 dGH
Group size ✓8 or more
Temperament ✓Peaceful
Swims at ✓Middle
Care level ?Moderate
Diet Omnivore
Lifespan ?Unknown
Size in shops 2–3 cm
Growth Medium

Behavior

Peaceful shoaler that prefers warmer, softer water than the neon tetra.

Food

Small pellets, flakes and frozen foods.

Tap a food to see what it is.

Male or female

Male Cardinal tetra
Male
Female Cardinal tetra
Female

Mature females are noticeably rounder-bodied and a little larger than males.

Health

Common problems. Tap one to see the signs. This is a guide, not a diagnosis.

Breeding

Egg-scatterer ·

Egg scatterer bred in a dark tank with soft, acidic water (pH 5.5-6.5, gH 1-5). Eggs hatch in 24-36 hours, and eggs and fry are light sensitive. It is commercially bred on a large scale.

Pairing

Buy a group of wild-caught or captive-bred fish. Use a group of 10 or more and condition well.

Setup

20-40 L tank with very soft, acidic water (pH 5.0-6.0), dim light, a dark bottom and fine mops or moss.

What starts it

Very soft acid water, cooler temperature drop and dim light.

Eggs

Up to 100-500 eggs reported in good spawns; hatch in about 24 hours. Success is often low.

Raising the fry

Feed infusoria, then rotifers and fresh baby brine shrimp. Fry are sensitive, so keep water soft and clean. Grow out in dim light.

Common mistakes
  • Using hard or neutral water
  • Bright light that kills eggs
  • Using unconditioned wild fish
Full breeding guide, day-by-day plan and simulator →

Where it lives in the wild

RegionRio Negro and Orinoco basins – Brazil, Colombia & Venezuela
Rivers and lakesMiddle Rio Negro (around Barcelos) and upper Orinoco tributaries
HabitatAcidic blackwater streams and flooded forest
Native rangeAbout 600 km across
See it on the world map

Plants that suit it

Alternanthera reineckii

The story of the cardinal tetra

Named after the publisher Dr. Herbert R. Axelrod. Many are still wild-caught around Barcelos on the Rio Negro in Brazil, where the fishery is a major source of local income, though it is also commercially bred on a large scale.

The cardinal tetra was described by Leonard P. Schultz in 1956 from fish sent to the USA and named after Herbert Axelrod. It quickly rivalled the neon in popularity. Many cardinals are still collected by local fishermen in the middle Rio Negro, a fishery that provides income for riverside communities.

First described by Leonard P. Schultz in 1956. Named for Named after aquarium publisher Herbert R. Axelrod.

  • Its red band runs the full length of the body, unlike the neon's half-length red.
  • Barcelos on the Rio Negro holds an annual ornamental fish festival celebrating the cardinal and discus.
  • Wild cardinals live in water so soft and acidic that few other fish thrive there.

Sources

15 facts checked with sources