Cardinal tetra
Paracheirodon axelrodi
FreshwaterFish
Care at a glance
- Temperature
- 73–84°F
- 23–29°C
- pH
- 5.0–7.0
- Adult size
- 1.8 in
- 4.5 cm
- Minimum tank
- 16 gal
- 60 L
- Temperament
- Peaceful
- Social behavior
- Schooling
- Swim level
- Middle
- Difficulty
- Easy
- Breeding
- No record
- Rarity
- Very common
- Family
- Characidae
- Origin
- Brazil
Overview
Keep them in a school of six or more, and honestly a dozen or more looks far better and settles them down. They swim in the middle of the tank and a 60 liter is plenty for a group. They are peaceful and eat small foods readily: micro-pellets, crushed flake, and frozen brine shrimp or daphnia. Soft, acidic, stable water is the main thing they ask for, so let a tank mature before adding them.
In the wild
Cardinal tetras come from blackwater and clearwater streams in the Amazon, especially the Rio Negro and Orinoco systems, under heavy rainforest shade. The water there is very soft, acidic, and stained dark by tannins. To match it, use a dim tank with driftwood, leaf litter, and gentle flow, soft and acidic with a pH on the low side and temps in the mid to high 20s C.
Good to know
This is a small characin in the family Characidae, reaching about 4.5 cm. The red stripe runs the full length of the body, which separates it from the similar neon tetra. Most cardinals in the trade are still wild-caught, so they can be a little more sensitive to water quality than tank-bred fish.
Did you know
The red and blue stripe is structural color, made by stacked crystal-like cells that bend light rather than by pigment. The fish can tilt those cells to dim or brighten the blue, which is why a stressed or sleeping cardinal looks washed out and a settled one glows.
Weekly picks
Tank mates
Cardinal tetra is a peaceful, schooling species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.
Oil catfish
Duringlanis perugiae
Freshwater2.4 in (6 cm) · 15 gal (55 L)75–82°F (24–28°C)
Clown killifish
Epiplatys annulatus
Freshwater1.4 in (3.5 cm) · 15 gal (55 L)68–79°F (20–26°C)
Gold rabbit snail
Tylomelania gemmifera
Freshwater2.8 in (7 cm) · 16 gal (60 L)75–82°F (24–28°C)
Epicharis tetra
Hyphessobrycon epicharis
Freshwater1.6 in (4 cm) · 16 gal (60 L)73–82°F (23–28°C)
Darter tetra
Characidium fasciatum
Freshwater2.8 in (7 cm) · 16 gal (60 L)68–79°F (20–26°C)
New Guinea blue-eye
Pseudomugil novaeguineae
Freshwater1.8 in (4.5 cm) · 15 gal (55 L)79–86°F (26–30°C)
Common questions
What size tank does a Cardinal tetra need?
A Cardinal tetra needs at least 16 gal (60 L). It spends most of its time in the middle.
What temperature and pH does a Cardinal tetra need?
A Cardinal tetra is comfortable at 73–84°F (23–29°C) with a pH of 5.0–7.0.
How big does a Cardinal tetra get?
An adult Cardinal tetra reaches about 1.8 in (4.5 cm).
Does a Cardinal tetra need a group?
Yes. A Cardinal tetra is a schooling species and should be kept in a group, not singly.
Related species
1.5 in (3.8 cm)11 gal (40 L)70–77°F (21–25°C)Neon tetra
Paracheirodon innesi
1.5 in (3.8 cm) · 11 gal (40 L)
1 in (2.5 cm)15 gal (55 L)72–86°F (22–30°C)Green neon tetra
Paracheirodon simulans
1 in (2.5 cm) · 15 gal (55 L)
1.8 in (4.5 cm)20 gal (75 L)73–82°F (23–28°C)Garnet tetra
Hemigrammus pulcher
1.8 in (4.5 cm) · 20 gal (75 L)
1.8 in (4.5 cm)17 gal (65 L)75–82°F (24–28°C)Head-and-taillight tetra
Hemigrammus ocellifer
1.8 in (4.5 cm) · 17 gal (65 L)
1.8 in (4.5 cm)16 gal (60 L)68–79°F (20–26°C)Mayan tetra
Hyphessobrycon compressus
1.8 in (4.5 cm) · 16 gal (60 L)
1.8 in (4.5 cm)20 gal (75 L)72–82°F (22–28°C)Ornate tetra
Hyphessobrycon bentosi
1.8 in (4.5 cm) · 20 gal (75 L)