Cardinal Tetra (Paracheirodon axelrodi)
The Cardinal Tetra is one of the most iconic freshwater aquarium fish, loved for its brilliant electric-blue stripe and vivid red lower body that runs almost the full length of the fish. It is often compared with the Neon Tetra, but the Cardinal Tetra usually has a more intense full-length red stripe and tends to prefer slightly warmer, softer and more acidic conditions. In a mature planted aquarium, a good shoal of Cardinal Tetras creates a stunning flash of colour through the mid-water area.
Common Name:
Cardinal Tetra. Also commonly referred to as the Red Neon Tetra, Cardinal Fish or Cardinal Neon Tetra.
Scientific Name (Latin):
Paracheirodon axelrodi
| Specification | Value |
|---|---|
| Size (adult) | 2.5 cm |
| Water Temperature | 22-26°C |
| Water pH | 5.5-6.5 |
| Water Hardness | 1-5 dGH |
| Compatibility | Peaceful community fish; avoid with aggressive species |
| Shoal Size | 6 or more fish recommended |
FAQ
What is the ideal water temperature for Cardinal Tetras?
The ideal water temperature for Cardinal Tetras is between 22°C and 26°C.
Do Cardinal Tetras need to be kept in a group?
Yes, Cardinal Tetras are social fish and should be kept in a group of at least six to enhance their natural behavior and coloration.
What type of water conditions do they prefer?
Cardinal Tetras prefer slightly warmer, softer, and more acidic water with a pH between 5.5 and 6.5.

Lily Lawrence –
I’ve had a shoal of Cardinal Tetras for three months now. They are incredibly active and their red and blue colors shine beautifully in the mid-level of the tank. The tank looks vibrant, especially during the evening light. They are easy to care for and don’t stress other fish in the community.
Megan Thomson –
The fish arrived healthy and seem to be adjusting well. I noticed they swim in tight groups and their colors are more vivid when the tank is well-planted. I keep them with other peaceful species and they coexist well.
Felicity Simpson –
This is one of the most visually striking fish I’ve added to my aquarium. The red stripe runs from head to tail and stands out in any setup. I keep them in a planted tank with soft water, and they thrive in the conditions.